Sansui DD SR-737 TT speed problem

[jd-audio]

I have bought a 1978 Sansui SR-737 PLL-SERVO DD TT some time ago. Speed was a bit off, but with some fine tuning on the pots inside it was ok again. With only one issue remaining : On 33 rpm with start-up the TT turned the wrong way for maximum half a turn (or less), and then resumed in the right direction. Strang enough this only happens on 33 rpm and not 45 rpm. But now (after a few weeks with perfect speed on both 33/45 rpm) the TT can not keep its speed correctly: it slowes down a bit and gets back to correct speed approx. every second on both 33/45 rpm. I can not correct this with any pots inside. I can change speed, but it keeps on "pulsating" every second.
What can be wrong?

 

[hakaplan]

If you haven't already done so, I would spray deoxit on all the pots and the 33/45 switch. Then, I think this thread has the rest of the answer:

http://www.audiokarma.org/forums/showthread.php?t=124900

 

[jd-audio]

Thank you Howard! The thread really helped.
I have disassembled the sensor in the motor, cleaned it an assembled it again. That did the trick. The "pulse" problem is gone!