well tempered motor speed ?

2-3 hours of CONTINUOUS play?? That's one LONG playing record; is it 2 rpm or something??!!

Seriously, in all my years with my WTT and now my Basis I never had this problem. Since no one else has responded, I would suggest calling or contacting Well Tempered, not sure if lubricating can handle this and they were very helpful to me years ago when I had questions. If the motor is defective and it's under warranty they'll likely send you a new one (and they might even do it if it's not under warranty, if they're like many high-end companies).

By the way, have you been giving the belt a half-twist? Unlikely to remedy this problem, but I always found that the table sounded better with that tweak!

Take the belt at the pulley on the motor and just twist it so the side that was contacting the pulley is now on the outside, that's all! Don't need lemons, elbows on the table, playing partners or the like. One of the original tweaks for a very tweakable TT. I don't know if the belt twist will solve the problem, but it's worth a try anyway, and it does improve the sound for some reason.