Music Hall mmf-7 spins faster


I have a Music Hall mmf-7 turntable (EAR 834P phono preamp) and it spins faster than normal. I bought a new motor and a new belt from Roy Hall, but it didn't change a thing. I borrowed my friends' motor (he has an mmf-7.1): no change... I even bought a Pro-Ject Speed Box (on Roy Hall's advice): it still spins faster. My cartridge is a Sumiko Blackbird. I really don't know what much else to do: any ideas? Did someone run into this problem?

I am desperate.
lrmellon
Measure the diameter of the platter on both units. Try and find someone who has a set of calipers. They are used by machinsts to make precision measurments.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96509

I have a MMF-7 with the speedbox and am V happy with it, till I can get a VPI and then a Teres. ;)
I am currently away from home; I will resume all (measurements, swapping parts, etc.) upon my return next week. Thanks all.
I am back with the conclusion: there isn't any.

Twad was right: the mmf-7 is a joke. With the new motor, it almost does not spin at all. I don't see any reason to use my time trying to understand what's wrong with this turntable. I'll be using the mmf-7.1 for the shortest time period possible and buy a VPI. Cheers all...
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No, I didn't. Thanks for letting me know. I will have to pass however. The VPI purchase will come some time in the second quarter of 2010 (at the latest), preferably a ScoutMaster. Thanks again...