Beogram 4002 DC Motor Restoration: Oil Infusion of the Bearings and a Shiny New Pulley from Austria

Another Beogram 4002 DC platter motor appeared on my bench for restoration. This motor arrived from Virginia. This shows the motor:

It came with a strangely worn pulley, which had a crease where normally the 'crown' of the pulley would bulge to keep the belt centered:

The motor barely ran when I bench tested it. I took it apart to extract the bearings for oil infusion:

The bearings are the two small donuts on the black pad.

Looking at the parts of the motor revealed that someone already had opened this motor and tried to lubricate the bearings. This caused the commutator and the brushes to get oily, which explained that this motor did not run well when I tested it. Oil has a tendency to wet most surfaces it can get onto, and this is why this motor stopped working. The excess oil that was squirted into the bottom bearing crept onto the commutator and that was it. I bolted the brush carrier back to the enclosure bottom (to protect the fine wires that go to the pickup coils) and then put carrier and rotor in water with some dish washing detergent:

Then I ultrasonically cleaned the parts, which resulted in an emulsion between the oil and the water:

I extracted the parts and ran them again in pure isopropyl alcohol to remove the water from the parts.

I immersed the bearings in oil and pulled a vacuum:

Immediately, strong bubbling started indicating that the oil infusion process had started. After about two days the bubbling stopped and I extracted the re-infused bearings and wicked the excess oil away:

Then I put the motor back together and installed a new pulley:

This pulley came from Vienna in Austria. They are CNC machined in a local shop over there. They are available to other B&O enthusiasts. Just send me a message and I will get you in touch. These pulleys are an exact replica and drive the belt very well.

Then I put the motor into one of my 4002s for testing with the BeoloverRPM device, which allows logging the RPM for extended periods of time:

This is the curve I measured after about 24 hrs:

This looks pretty much as good as it gets, i.e. this motor is ready for duty again.