NAD 502 - disc without spinning (don't start after FOK)

At this model I have perform service work and maintenance several times. But the currently device has an unusual error:
The disc try to start but does not really running. For reading in the TOC the correct speed is not reached. When I turn on the compact disc by hand while the time of start trial immediately after FOK the running process goes on and the disc read in the TOC. By pressing the button "PLAY" I must also do turning the disc by hand because otherwise the disc in this phase even only tried to run.
Until now I haven't observe this. Actually only the Spindle-Motor or the driver IC from Toshiba must be defectice resp. faulty. Are there also additional causes ?
Thank you very much for your helping.
Oh my dear - one never know when old posts will come back to haunt you.

I know from memory, that the pug on the spindle motor was not always at the correct height. The consequence was that the push-pull transistors of the focus driver stage were heavily overloaded (thermal stress, burned solder joints) and were subsequently destroyed (mostly one of both).
The use of transistors in TO126 outline and additional heat sink was the solution in my case.
An other drawback was the too small PCB mounted heat sink on the main board.
Removing of the heat sink and mounting the TO220 Transistors on the back plate increases reliability dramatically due to the large cooling surface - even if the thermal conductivity is worse with sheet steel than with aluminum.

But in your case I would purchase another cd player, where is in use the same loader KSL2101ABM or at least the same transport mechanism.
Then you have the opportunity to exchange questionable parts for saving time.
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