Mac hard disk drive, head sticking

Last update Feb 7 2021. Edited by Herb Johnson, (c) Herb Johnson, except for content written by Lorne Hinz. Contact Herb at, an email address is on that page..


In June 2020 I received emails from Lorne Hinz, about problems with a Mac SE's hard drive. He was determined to diagnose the drive's problems, and so he sent me the details of his tests and evaluations. He discovered "head stiction" on his drive. That's where the disk drive read/write heads become stuck to the disk drive rotating platters. So, the drive doesn't spin up and operate. As his notes were methodical and very informative, I'm providing his account on my Web site, with his permission.

Caution: You'll read that he has opened and worked on his SCSI hard drive. I can't advise others to do this, it risks damage and loss of data. As Lorne points out, he had nothing to lose upon a nonworking drive. But use this information entirely at your own risk. - Herb Johnson

Goals and methods, by Lorne Hinz

Thanks Herb for the two very informative emails. It is a pleasure dialoging with you. [My technical background is 40 years work in Research and Development in telecommunications.] Now my new learning challenge is to try and restore my Mac SE. I am a Mac novice, so I am glad I found an expert like yourself, Herb.

So, my goal was just to get my old Mac operational, as a working antique, for myself, and grandkids. I have been searching on local-neighbor sites, to see if anyone has some old MAC ready for the trash that may have a drive that still works. Just to get it operational, 20 Megabyte is large enough. My questions about larger sizes were with respect to if I find an older larger drive, how large will work. I am concerned that I may find a larger drive, but it is too large to work with the Mac SE and OS 6.0.4.

What I've experienced so far, is that my Mac SE disk drive has "stuck" heads. Here's the details.


- Mac SE purchased in 1988 with one floppy disk drive, and one 20 Megabyte RoDyne model R0652 Hard disk

- Power On, Mac comes up with a sad face, as it is trying to boot from the Hard Drive but the Hard drive is not working

- Insert a Floppy disk that has OS 6.0.4, and the Mac SE introduction tutorial

- Mac SE boots, and tutorial program with graphics works.

Those steps prove that the motherboard is mainly working, processor, memory, CRT works, floppy works, mouse and keyboard work. So it appears the Mac is working except the Hard Drive.

Hard drive tests

- Disk Utilities Disk: no SCSI drives are found. This could be the SCSI interface on the motherboard, the SCSI control electronics on the Hard Drive, or the physical hard drive.

- Least invasive things first: with power off, unplugged and re-plugged in all connectors several times;...still no SCSI drives found Note: Most early connections do not support "HOT" connect / disconnect, so always power off when removing and attaching cables.

- Tried knocking and tapping the drive in case the heads were stuck. If I can see that the Hard drive turns and the heads freely move in and out, then it may be either: 1) Mother board SCSI electronics, 2) Hard drive SCSI electronics,or 3) Hard drive platters or heads are bad.

Operations on the hard drive

[sticky drive]

I cannot [easily] tell if the hard disk is actually turning, without removing the hard disk sealed cover. As the disk is unuseable, with nothing to lose I removed the cover of the hard drive. I tried to very gently rotate the disk one sixteenth of an inch, or just a degree or two of rotation.

I can see as I try to rotate the disk that the very tinsel-thin metal holding the heads bends when I try to rotate the disk. [in use] the heads are moved from the outer to inner circumference of the disk, by a stepper motor which drives the head cam leaver.

I tried moving the head cam to move the heads in. Now I can see the very thin tinsel metal holding the heads, starts to buckle from the pressure.

The above steps prove that the heads are stuck to the parked outer edge of the disk. This sticking is referred to as "stiction".

Actions and results

[sticky drive]

Note: in the image, you see reflections of the head on the platter. There are four heads, one on each side of two platters. - Herb

With jeweler screwdriver, I gently pushed on tinsel metal holding the heads, taking great care not to touch the disk platter Soon able to get the heads released from the platter, so they can gently be lifted [a small amount] off the platter. This disk has 2 platters, and each platter is double sided so there are 4 heads.

After I got all 4 heads free, I could now rotate the disk, and the disk head thin tinsel holding arms were not bending. So now I know the heads are not stuck and the hard drive can turn, if the electronics is working to instruct it to turn and the heads move in and out.

I left the cover off and connected the drive back to the motherboard. Power On, disk first rotates up to speed, then see the disk heads moving back an forth across the disk. The Mac SE boots [from the hard drive]. I see Hard Drive [on the Mac's desktop screen], I can click on the hard drive and see and open all files. So I did several cold restarts to make sure the Drive would start back up from a full stop; worked perfectly

But after a few hours of powered off / disk heads parked, tried to restart, .... and grrrr .. heads stuck again, disk cannot turn. The heads or platter material must have deteriorated that makes the heads stick to the disk platter. I am very leery that any cleaning solution will either ruin the heads and disk, or leave a residue that will just cause future sticking.

But with nothing to lose I tried putting 70% rubbing alcohol on the disk / heads to try and clean them. (I would not use Acetone (nail polish remover) as it will likely damage the disk or heads [or the magnetic surface].) This made the disk easier to rotate, but again after a few hour the heads are sticking again. (Note: I found out months later from my EE son, that I should use 99% electronics cleaning quality alcohol as it leaves almost no residue. The 70% may still have left some residue.)

Power Connector problem

When plugging the Hard Drive power connector back into the mother board, I noticed one of the Pins was loose. On careful inspection the Pin soldered to the mother board was either a "Cold Solder Joint"; or during the numerous removes and installs I had broken the solder connection. I re-soldered all the connectors pins to the mother board.Did I have two problems, sticking heads and intermittant power? I will never know, but the platter was still not moving after the above power connector fix. I confirmed getting +5V, and +12V DC to the Hard Drive.

What next?

I will next try Herb's suggestion of trying a bit of Teflon [plumbing pipe fitting] tape and rubbing it on the outer parking edge of the disk. [That hopes to leave a Teflon residue to lubricate the heads and platters. - Herb]

I did find a specially formulated hard disk lubricant, but this appears for disk manufacturers and not for commercial sale. Hard disk surface lubricant "MORESCO PHOSFAROL" is a special lubricant for lubricating the gap between the magnetic head and the magnetic disk of the hard disk drive. It protects the information recorded on the disk by forming a thin film at the nano-inches, improving the reliability of the hard disk.

A more drastic fix

With nothing to lose I removed both disk platters. Now I could take a Q-tip with alcohol and gently clean the heads.I then took Teflon tape and dragged it between the heads.Then I reinstalled the platters. Now, manually turning the platter the heads seemed to be very free and not sticking. But now, the hard disk will not spin up, even when I can confirm the heads are not sticking. So now I have an electronics problem.

Note from Herb: If asked, I would have advised against removing the platters. It changes the alignment between the platters and likely will make the drive useless, even if the disk can spin up. See my comments later in this Web page for an alternative. - Herb

The disk motor, or electronics may have gotten burnt out because the platter not able to turn, or in the process of all this work some chip got ESD damaged, or shorted??? I will never know if the platter removal and head cleaning worked or damaged the disk or heads. I have an oscilloscope and if I had the circuit diagram and test guide for the Hard Drive electronics I am sure I could fix it. But with no circuit diagram, my only option is to buy a used compatible drive.

So at this time I am just using the Floppy drives to play games.

- Lorne Hinz

Comments by Herb

This is good work, to diagnose a Mac SE's problems down to the SCSI hard drive, and then to work out the exact problem and attempted fixes. Lorne proceeded with care, took note of progress and results, and came up with strategies. He made decisions about relative risks.

On diagnosing the drive's actions. With experience, one knows the sound of a rotating hard drive. They vary but often old hard drives are pretty noisy as they spin up. Lorne was new to the experience and otherwise may not have known this.

On lifting the heads from the platter, I would have been more cautious and used plastic tools not metal tools. Beyond scratching the platter or heads, the jeweler screwdriver may have been magnetized. But he took care and the fact that the drive could read successfully suggests as much.

On removing the platters. If asked, I would have advised against this. It changes the alignment between the platters and likely will make the drive useless, even if the disk can spin up. My advice was to lubricate the platters, by rubbing a lubricating material - Teflon tape -on the edge of the platters. That could have been done without removing the platters. It need not be done on the entirity of the disk platter surface. Material on the edge would be carried across the platter by the heads. This is a desperate solution to a desperate problem.

On opening the hard drive. This must be done in a clean and dust-free environment. Dust in the drive will jam the heads and scratch the platters. It's very risky, but as Lorne noted one may not have other choices. Actually: there is an alternative.

Release the heads

An alternative way to break-loose the heads, is the following procedure. First, remove the drive from the computer. Then, find a soft surface - a towel or pillow on a table. HOld the drive a few inches above the padded surface, holding it firmly from above so that the flat sides of the drive are parallel to the flat surface. The tips of your fingers and thumb will be on the narrrow sides of the drive. Hold the drive like holding the lid on a jar.

Then, flick your wrist in a twisting rotation fashion - like opening a jar - but do so rapidly a few times. Keep the drive flat and horizontal as you do so. And of course - don't drop the drive! That's what the cushioned surface is for, if you do drop it.

What you are doing, is rotating the disk platters by inertia. Or at least, exerting a momentum force on the platters. The "stiction" problem is, the drive's rotation motor doesn't have enough force to break the stiction; you are using momentum instead of the rotation motor.

The subtle thing to notice, is if you can *hear or feel the disks rotate* after this action, while it's still in your hands. You may or may not. Of course, when the drive is powered up again - either you hear the drive spin up, or you hear it not spinning. Most old drives are pretty noisy when they spin and seek. - Herb Johnson

A bit of Lorne's background

I worked in R&D for a tier 1 global telecommunications company for 40 years. When micro's first came out in the late 70's / early 80's I was already a first level manager, so I never got to personally design micro circuit boards nor program them. The last 10 years I was an R&D VP and I led multiple different divisions, each with 1,500 to 2,500 employees with labs in 10 countries. Over the years I managed hundreds of employees doing computer hardware and software design, but I had not done it myself.

So to keep learning, my retirement hobby is designing home automation systems: whole house "Water Flow Sentry to avoid abnormal water flows, smart attic fan controllers, thermostat controllers, irrigation and pool fill controllers, security alarm controllers, garage door open monitoring controllers, etc. I use TI MSP430 micro's, I design and build the analog and digital interface circuits, and have written over 50,000 lines of C-code for these controllers. My controllers send me twice a day status / data, or send immediate data for alarm conditions. - Lorne Hinz

A P.S. from Feb 2021

A mid 1990's lighting strike near our house damaged many electronics items, but only now that I am retired did I have time to try and fix the items that required more in-depth work. I was able to fix my Technics RS-B78R audio cassette tape deck. I was able to fix my Pioneer SX-7 stereo receiver and Power Amp, So the total 2020 fixing score is 3 wins (the SE still works), and 1 defeat! - Lorne

Contact information:
Herb Johnson
New Jersey, USA
To email @ me, see
see my home Web page.

This page and edited content is copyright Herb Johnson (c) 2021. Copyright of other contents beyond brief quotes, is held by those authors. Contact Herb at, an email address is available on that page..