I have a cnc mill that has run with Galil for many years now. We've had occasional trouble with a servo buzzing or vibrating back and forth a very short distance while at the stop position. its been present for a long time but has gotten worse recently.

These are DC brushed servos running in toque mode using AMC brushed servo amps, model 30A8.

I first re-tuned with WSDK using general tuning and got
P 60 D400 I40 no help with the buzzing

Then I tried reducing everything 10% (55,360,36) and 20%(49.5,324,24) then tried a big drop in I (49.5,324,24) and then a big drop in D (49.5,275,24) No help at any setting.

What should i try?

Thanks

Karl