Sometimes the tolerances of the newer tables are a bit different from the old and I would think the new belt is designed around the newer models. I had a speed issue with my Basis when I changed to a new belt and the problem was corrected with a new motor pulley. You might try a new standard Rega belt and see if it works better.
Rega reference belt disappointment
My RP3 is about 11 to 12 years old and has the original belt and I thought it might be time to replace it. I figured I would get the Reference EBLT belt, and why not? Rega’s site shows how much better it is with respect to wow and flutter, right?
The disappointment comes from testing both old and new with my phone RPM APP.
The old belt has a WOW of around plus or minus 0.08 %. The new “Reference” belt shoots up to plus or minus 0.27%
Ok the App may not be the most accurate with respect to the actual value displayed but the repeatability would suggest the new belt is worse than the old. So what the hell, Rega? I will give it a few more hours to see if it settles in but so far I’m disappointed.
I tried to post my pic’s of the app results but couldn’t figure out how.