I am working on a Beogram 3400 turntable. I have lubricated the tonearm lift piston, and have cleaned the cogwheels and other mechanisms. It all works perfectly----for a while---then unexpectedly (and seemingly randomly, though I'm not sure about that), the tonearm does not move over the record when the START button is pushed. If I gently nudge one of the plastic cogwheels, then everything goes into motion as it should.
I don't know if this is a lubrication problem, or a problem with the electronics.
Help would be appreciated.