Beogram 4004: DC Motor Restoration

I recently received a Beogram 4004 DC platter motor from a customer in Indiana for restoration. This shows the motor as received:

I tried to run it with my bench supply, but no response except a high current...not a great sign. The pulley came right off...a sign of previous 'creative human interaction'! I took the outer housing off, and saw that the bearing spring was peeking out above the top bearing:

This indicated that the bearing was below the spring, which was confirmed when I took out the rotor:

I extracted the bent bearing spring:

I also saw that the feedback pickup coils on the spring carrier have curiously 'melted' plastic spool tops:

Not sure what happened there...I went ahead and disassembled everything to get the bottom bearing out:

The bearings are the two small donuts on the black pad. I immersed them in oil and pulled a vacuum. Immediately vigorous bubbling started, indicating that air was drawn from the pores of the Oilite bearing material to make room for fresh oil interdiffusion:

After about 72 hrs the bubbling stopped. I tried to restore the bent bearing spring as good as possible so the bearing could be held in place again safely. Then I reassembled the motor and installed it in one of my Beogram 4002s for a 24 hrs RPM stability test with the BeoloverRPM device. The BeoloverRPM allows logging of the RPM over long periods of time.

This is the curve I measured:

It seems I was lucky with the bearing spring. This RPM curve is pretty much as good as it gets. This motor is ready for duty again!