DC Motor Speed Issues

I just setup a Redpoint tt and I can not get the speed to stabilize, I am using the 1/2 mylar belt with aDC motor.. Anyone have any ideas???
Is the table designed to be driven by a flat mylar belt or by an O-ring belt?  The belt thickness affects the platter speed.
Does the motor pod have any adjustable motor trim pots which allows for fine tuning of speed?
yes it does I think I have it now...