Beogram 4002: DC Motor Restoration

A Beogram 4002 DC motor recently arrived for restoration from Iowa. This shows the motor as received:

I took it apart to get the bearings out. Most Beogram 4002 and 4004 motors need their Oilite bearings re-infused with oil. Such bearings are made from porous brass, and after operating the motor for some time the oil in the pores is drawn out and the bearings run dry. This causes RPM variations and eventually the motor will seize and stop running. This shows the motor disassembled:

The bearings are the two small donuts on the black pad upfront. I immersed them in motor oil and pulled a vacuum:

Immediately vigorous bubbling started. This indicated that the air in the pores of the bearing material was pulled out by the vacuum. This process creates space for the oil to diffuse into the bearing. After about 24 hrs the bubbling stopped, which indicated that the infusion process had completed. I extracted the bearings

and re-installed them into the motor housing:

I use a specially made 3D printed tool for pressing the tabs of the ring that holds the upper bearing in place back into their original shape.

This shows both bearings back in place:

I put the motor back together and installed it into one of my Beogram 4002s for a 24 hrs RPM stability test with my BeoloverRPM device:

The BeoloverRPM device allows logging the RPM in 10s intervals for extended periods of time, perfect for spotting intermittent RPM issues. This motor passed with flying colors:

This is as good as it gets for the Beogram 4002 DC motor. This motor is back in business! Time to send it back to Iowa!