Agree with Stringreen, wobbling is most likely caused by the cartridge picking up a signal at it's resonant frequency. That may be the motor, belt, bearing or some external source - or perhaps the cartridge is faulty? Have you tried another?
If the table seems to be running smoothly (motor not excessively vibrating etc) I'd try a different cartridge first.
If the table seems to be running smoothly (motor not excessively vibrating etc) I'd try a different cartridge first.