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! :)
Check the side to side bearing play on the motor.  If you got 18 years out of that motor you did well.  Those Maxon motors do not like a lot of side load.  If you can do your own work check out the DIY forum and the the motor controller threads over there.  Bill/ Pyramid has a great thread with almost step by step instructions.

Enjoy the ride

I'm not sure which motor Chris used on the early Teres tables but if it's the same motor Thom Mackris used in his Galiber table that motor is no longer available. I emailed Maxon a couple years ago and this is their reply..

My name is Eugene and I am a Motion Control Applications Engineer at maxon. I received your inquiry for a replacement motor for your current S26, Precious Metal Brushes, 4 W (2326.933-12.111-050).


The motor that is the closest replacement for your S26 motor is the A-max 26, Precious Metal Brushes CLL, 4 W (110169). Please see below for the cross reference.


S26                                         A-max 26


Speed Torque Gradient (rpm/mNm):                     181                                         190

Speed Constant (rpm/V):                                             1330                                       1380

Torque Constant (mNm/A):                                       7.19                                       6.94

Have you cleaned the pulley / platter with rubbing alcohol?

Good Luck!

Have you checked with Chris?

I really miss an active and vibrant Teres community. I'm always interested in ways to optimize my table (essentially a cocobolo 245 w/ a Verus motor). I'd love to get my hands on a lead-loaded platter.
Those were the days when some real smart guys did some brainstorming and came up with rock solid ideas for the diy community.  Not a bunch of marketing b.s. or ego based crap.

The lead loaded platters are the real deal.  Mine are aluminum,  but heavy outer rim lead really helps almost any material.

Enjoy the ride
Tom, did you machine your own platter, or did you have it made? Forgive me if I've asked you this before (on this or another forum). I keep throwing this question out there waiting for someone to respond, "Oh...Let me introduce you to the guy who machined my drop-in replacement platter for the standard Teres bearing. He's done several and knows exactly what you need. They are heavy, fit perfectly, and look great!"
I did make my own.  One is 32 lbs other is 38.  Sold my PVC and straight aluminum ones.  Have a chunk of delrin which I will lead load next.  

Any machine shop could do this. Let them measure your current platter and the rest is easy.  

Enjoy the ride

Thanks to all who replied! The Maxon motor in mine is a Maxon 110189.
Believe it is still available. Chris told me he hasn't seen one fail yet. Told me to clean and lube the motor bearings, and inspect and clean the platter bearing, and to check the sensor. Will try and find Bill Pyramids posts on this subject. Thanks!!
Posting a follow up...I only reset the belt, and cleaned the sides of the platter (again). NO more problems!...it is again the ROCK STEADY friend it has been for 18 years. I don't think I did anything....really. I can't help but wonder if it was because of the high amounts of STATIC in the air when it was acting up? It can get really FREAKY dry out here in the West...like 3% relative humidity, which is about what it was when the table was acting strangely. Thinking that there might be a static charge building up between the mylar belt and the platter, I tried my Zero Stat on it. The EPROM didn't seem to like it...the motor sped up to max, and the red light stayed on. Plus I could actually see sparks arcing between the spindle and the motor! Could it have just been freaky static? I tried running an ultrasonic humidifier in the listening room, but it didn't seem to make a difference....
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.