Beogram 4004 DC Motor Restoration

A Beogram 4004 DC Motor arrived from Germany for restoration. This shows the motor as received:

When I tested it, it ran very noisily, a clear case for oil infusion. I took the motor apart and extracted the bearings. Sadly, I forgot to take a picture of the disassembled motor....this shows the bearings submerged in oil after pulling a vacuum:

Immediately, vigorous bubbling occurred as the vacuum pulled the air trapped in the pores of the Oilite bearing material. This created room for oil to diffuse into the bearing. After about 3 days the bubbling stopped, i.e the bearing was again full of oil. I extracted the bearings from the oil and installed them in the motor. Then it was time for testing the RPM stability. I inserted the motor into one of my Beogram 4002s and ran it for 24 hrs while logging the RPM with my BeoloverRPM device:

This is the curve I measured:

this is pretty much as good as it gets with the Beogram DC motors, i.e. this motor is ready for duty again!