Technics Turntable

Hello,
I am working on a Technics SL-D303 turntable that I recently acquired and need a bit of help. The turntable has very low torque, will not pull up to speed, but will control the speed if I "help" it get turning. Recapped the circuit board, checked all resistors and replaced all the semiconductors, but the problem persists. I did disconnect the Hall Effect Sensors and there is no change in the way the turntable reacts. I would replace the HE sensors, but I have not been able to locate replacements.

Could the platter magnet we weak? What function do the Hall Effect Sensors serve in the drive circuit?

Thanks for any help you can give me,
David