Beogram 6000: Oil Infusion of AC Platter Motor Shaft Bearings

I recently received the AC platter motor of a Beogram 6000 (Type 550x) from a customer in the Netherlands. The motor exhibited knocking noises that could not be adjusted away by reducing the motor voltage. This is usually a sign of dry motor bearings. My remedy for this issue is reinfusing the Oilite motor bearings with synthetic oil under vacuum.

This shows the motor as received:

After a trip to my garage for drilling out the rivets that hold the enclosure together, I disassembled the motor:

It is important to keep the parts on the shaft in their original order and orientation (the washers have an orientation, too!):

Unlike the later DC platter motors, there does not seem to be a straightforward method for removing the shaft bearings from the enclosure halves of the AC motors. Therefore, I simply put the entire enclosure into the oil. This is a bit messy, but it works well. This shows the initial bubbling coming from one of the submerged bearings while the pump labored to pull a vacuum:

A few minutes after the lowest pressure had been reached, the oil had foamed up:

These bearings were pretty thirsty! But I think some of the bubbling up air also comes from pores in the enclosure itself. The infusion process is completed when the bubbling stops. At that point, all the pores are again filled with oil. After two days, the oil became quiet, and I removed the parts from the vacuum chamber. This shows one of the bearings after I cleaned out the oil:

These bearings look pretty similar to the ones found in the later DC motors. They can also adjust their angle to minimize misalignment with the shaft.

I put the motor back together:

If you try this at home, make sure the stacked coils are re-inserted at the correct polarity (purple and green wires need to be on the same side as before, otherwise the motor will run backwards). Since opening these motors requires destroying the threaded rivets that hold the enclosure together, I developed 3D printed plastic parts (red) with integrated M3 nuts for the tilt adjustment screws. Note that without the rivets, the enclosure is mostly held together by the mounting screws after the motor is bolted back into its place in the Beogram. This is not an issue for the operation of the motor, but it needs to be kept in mind when the motor is reinstalled.