I recently helped a friend to repair a Linn Valhalla power supply pcb. It would seem that these are prone to particular failures and a common one is low motor torque in which the motor buzzes or vibrates since it is too weak to drive the platter. This turned out to be R32 (560k) on the board. R33 had also deteriorated with the ceramic body breaking up. I have uploaded the circuit as a png and pdf file which some may find useful.
If you are having motor problems I would first replace these 2 resistors R32 and R33. Failing that then the next step is to replace the small orange caps around the logic chips if the motor does not turn at all.