VPI motor - upgrade to 300 rpm?

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.

Yes, true, the newer SAMA from what I can see as well, is basically empty. Nothing inside, but a Foam Sheet isolating-seperating the bottom of Motor Case from the Run Capacitor.

But, the 600rpm Motor is not inheritly bad as far as speed stability goes, and if working properly, is not prone to the large degree of speed variation that you are appearing to notice.

So, with that said, yes, the Motor could be at fault, and I imagine if it is doable, one could then possibly opt for either the 300rpm Motor, or otherwise, a new 600rpm Motor should do the trick.

It will be VPI that may have to answer your questions, if the 300rpm Motor will be a simple swap, or will one have to modify the SAMA Case in order for it to fit? We can assume that a different Pulley would indeed be needed. The question is, does VPI have the correct Pulley that will work with a SAMA. Meaning, will it be long enough to protrude far enough, and up through your Plinth to reach alignment with Platter? That is an unknown to me?

Having to glue the pulley, I then assume you once had either slippage, or wobbling of the Pulley, to require gluing it to the Shaft?

I think we can all agree, that the Base on which your Table, and SAMA rest upon should not be an influence of the Motor's speed stability, that this would be caused by something else? But what?

The only other influence that I can think of, in regards to speed fluctuation, would be the VPI SDS at fault? One would have to test the SDS to find if any fluctuations in voltage and/or line frequency are taking place?
Mark

If you have an SDS then there is one other thing I can highly recommend that you try. Get rid of that vibration prone VPI rubber belt and find some silk thread. Tie a basic knot in the ends and use that instead. You will definitely have to adjust the speed to compensate for the thread's smaller diameter sitting down in the pully groove. You will also definitely need to give the platter a push-start by hand.

The PRAT will increase dramatically, with more detain and better space and air. Not a small improvement and easily one of the best things I did for my VPI.

Thanks! I think PRAT is what I am looking for, and want to try the silk thread variant. What kind of basic knot do you use?
The question remains, what is the best motor, is there a sonic profit with 300 rpm? Since no-one here has answered, I have mailed VPI about this.

Please keep in mind, that VPI is on vacation till Jan 11 I believe. Mark