I have a Pioneer PD-701 multi-disc changer. When a cd is put in the cartridge and it is put into the player and play is pressed, it pauses for a second and then skips to the second disc (empty), then the third, fourth, and so on. So i took the cover off to see what's going on. It loads the cd into the optical pickup assembly, but the spindle motor never spins, and after a few seconds it skips to the next disc and looks for a cd there. If that is what's wrong i can get a new spindle motor for $14 http://www.partstore.com/ProductDetail.aspx?ProductSKU=5516114&ProductType=PART&ModelID=273935
However i'm not too sure this is what's wrong. Everything else appears to work fine...
Have you checked for voltage at the motor terminals to verify that the motor is actually receiving power? It's unlikely a DC motor these days. Normally they are brushless DC (basically AC) and might be a little hard to mesure without a scope.
also check the motor it self with an ohmmeter they should read in lo ohm,compare your reading with a working motor they should be close. i have seen some of them with worn out brush unless they are brushless.