If you push the lock to the side as shown you can then move the heads. I did that to insert the blue shim between the rubber stop and the head assembly. The blue shim sticking up on the right side is .005 inches thick. I later needed to add a second .002" shim to make it reliable. The shim will also prevent the heads from sticking again. The rubber bumper is down in the slot between where the two screws are and the blue shim. I didn't try to fasten the shims in place since I was primarily trying to recover the data. If the drive is going to be handled retaining them may be a good idea.
I did this with the drive not spinning. Dragging the heads over the disk surface isn't a great idea but it didn't seem to hurt it. Now that I know where the shim needs to go it may be possible to do it with the drive spinning but with this failure the heads want to stay against the stop and with the limited time the drive stays spun up it will be difficult to do it with the drive spinning. The drive will also retract the heads and spin down if you manually move the heads too far. More info
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Feel free to contact me, David Gesswein djg@pdp8online.com with any questions, comments on the web site, or if you have related equipment, documentation, software etc. you are willing to part with. I am interested in anything PDP-8 related, computers, peripherals used with them, DEC or third party, or documentation.
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