Sorry I don't have any clue to help you on the squirrel cage.
But the one thing I wanted to mention to you was to disconnect the solenoid
that controls the heads moving out when testing the disk packs. We had a
case where a bunch of disk packs were stored in a hot muggy environment for
about 9 months or so, and warped on us. When spun up, the disk will make
quite the shrill noise indicating it's warped, and if you don't disconnect
the solenoid, the drive will crash all over again.
I haven't worked on one of those drives in about 10 years...
TTFN
Andrew