@noromance - I can honestly say I think it sounds the same at 33 rpm.
The SRM Tec Deluxe Acrylic Platter for Rega comes with a large "rubberized band" that fits the outside edge of the platter to subdue unwanted micro vibrations in the platter
The original glass platter did weigh more than the acrtlic platter, so I added the sorbothane to the understide of the platter to give it some added "heft" -
Since I did not really play 45 RPM that much back then I didn’t test 45 rpm at that time of applying the sorbothane
Fast forward to today and i now have more 45 rpm albums, That’s when I discovered the issue - I thought it was the belt, but that was not the case.
Thinking back - I had the Mission sorbothane mat on the glass platter and it played without incident. But that was also with the original motor.
Perhaps there is something different about the Rega motor upgrade kit I installed?
- different control circuit - could that effect torque?
- Different motor - could it have less torque?
- who knows
The issue has been resolved to my satisfacton and it is sounding very nice at 33 and 45 rpm,
But it had me wondering there for a while :-).
Regards - Steve