August 28th, 2011, UPDATE. My sl-qd33 is back in sync. I fiddled blindly with the tonearm motor and record size detecting mechanism while powered-up.
I pressed the START/STOP button and the tonearm moved to cueing-up position and stops. The platter does not turn an inch. So, I reached in underneath and moved the record size detecting mechanism to a 'mid-way' detent position (I think). Then I start to rotate the tonearm motor by rubbing the worm gear and suddenly the motor and mechanicals start moving under own power. I remove my hand gently, and slowly lower the top half of plinth as I joyfully see the tonearm move over the LP and lower itself as it should.
Then I pickup the tonearm and move it to the last few grooves of the last track and in a few seconds the tonearm picks itself up, moves to its rest, lowers, and the platter stops. I am able to repeat this numerous times and I belive its back in service.
I want to thank everyone who has contributed to this site for their determination to keep these great old machines from the landfills and finding good homes - an inspiration to me too.