VPI motor - upgrade to 300 rpm?

You can easily pick up a new Hurst motor on the web. You don't even have to go through VPI to get it.

On another note, I believe there was some discusison about which motor was actually better. Something to do with the cogging effect, since the number of poles differ on each motor. Maybe someone else who has more knowledge of this will chime in.

What your problem may be, is the Drive Belt? When was the last time it was changed?

The SAMA Motor shouldn't be changing, or fluctuating speed, and the SDS should be providing stable voltage-frequency to the Motor.

But, if your SAMA is using the newer, "stepped drive pulley", that one can adjust speed at the pulley in very small increments by which little groove the Belt is placed on, it is possible that an old, or worn belt is wandering on the Pulley?

Those ridges on the pulley are very small. I'd try this forst before resorting to Motor swap-outs. Mark

Not sure yet if my first response will be posted, but besides the possible issue with the Belt changing places on the Pulley, another cause could be the possibility of your SAMA not remaining stationary?

I'm finding that out myself with a recent SAMA installation, that the stock rubber SAMA feet seem to be inadequate. My SAMA I note is beginning to pull towards the Platter, that I'm noting inconsistency of Belt Tension due to this "pull", I'm seeing the Rubber feet bend-lean under this pressure, and am in the process of retro-fitting my SAMA with a set of Herbies Tenderfeet.

They are a few mm taller, but a wider foot, at 1.1" x 1.1".

Other devices out there could be used. I think the important thing, will be providing a rock solid anchoring of the SAMA to whatever Shelf-Rack you use. Mark

Thanks for advice. First of all, my main problem was solved by oiling the motor and glueing the pulley to the shaft, as I wrote. It was not a drive belt problem. I use the SAMA with the SDS and have a special Bright star platform (sand box) with separate support for the SAMA. I have not noticed any "pull" with this arrangement, but will investigate, and agree with you on the "rock solid" goal. In my experience, everything that can be done to dampen the motor and make the belt perform as smoothly as possible is definitively worth it (so my Sama has extra damping, I even found a bit of bluetac under the top ring made a positive difference. I use a stethoscope and my finger to detect noise and vibration for the motor). I have not tried tenderfeet but already have a complex support system including three small bike tires below the sand box (cheap way to air suspension, and yes, it does help).
Thanks for the advice on the Hurst. Interesting to open the SAMA and see that 80 percent of it is just the metal support for the tiny motor. Since I probably need a new pulley along with a 300 rpm motor, I may go thru VPI. But the question, is this a sonic benefit, has not been answered.