David R Brooks wrote:

I once worked as a service tech on drives like that. Those magnets
probably came out of the head positioner, which is a *righteous* linear
motor. There might have been a nice DRO-like glass scale to go with it.
We were severely warned to keep hands out of that thing when the power
cord was in. If it detected a low-speed fault (like, the power fails), a
crowbar SCR dumped the 48V supply cap. into that motor coil, to drag the
heads off the disk instanter. You really did not want fingers in the way
of that...

Yes indeedy. I worked on a bunch of those in Chem dept at UNM.
14 inch removable platters. Thanks goodness we got rid of them
before I retired. The last while had Winchester drives on the
Mass Specs.
...lew...