Speed stability issues with my Teres turntable...

After 18 YEARS of flawless service, my Teres 155 series turntable has developed speed instability issues. Sometimes the red light comes on. But even when it doesn't, I can hear it. It's gotten to the point I don't want to listen to it anymore. I've already done the usual drills such as rebooting the motor (non battery version), replacing the belt, etc. The motor has STILLl got torque galore, so I don't think it's failing yet.
Could it be motor speed controller circuitry components failing? Hope not-I've got the schematic for that, but don't have the technical know how to trouble shoot that. I've already done a search, and will be looking into the bearing well, checking the bearing, and checking the tightness of the pulley. Any other suggestions would be greatly appreciated! :)
Good stuff. Do you have your platter bearing connected to ground?

While I love my Verus motor, I do miss the ability to start the platter spinning with a simple push (and also stopping it by hand). 
I have a Redpoint Model D tt and I had some speed issues a while back, I got a new motor from Maxon thinking that was the problem it was not. Same speed issue as before so I did some checking turns out it was the motor circuitry. I bought a cheap complete motor from the Bay and have never had any more speed issues. My next trick is to get the new motor and circuitry into my original motor pod then I will be a happy camper again...
Have you changed the spindle oil recently? I have a Teres from the 2nd diy group buy and had some speed instability a while back. It seemed to me like my platter had a little more drag than usual. I decided to change the spindle oil. The old oil didn't look that bad when I took it apart but it cleared up my issue. Good luck.
Yup...the bearing well is indeed grounded. Sides of the platter have been cleaned. I think now what it was was that a bit of lint got over the 'eye' looking at the bottom of the platter. Once I finally got that out, no more probs. FWIW, Chris now recommends ATF (any brand) when it's time to change the bearing oil. I'll do that next time I've got it apart.