For a few years my CD player would work for a while, then stop. I'd try cleaning it and the cassette after which it would work for a few days and then fail. Finally assuming I had nothing to lose, I decided to spray the hell out of its with WD40 while it was turned off. I stuck the nozzle into the loading slot and sprayed all around the inside for several seconds. I let it dry for a while, then reinserted the cassette. That was over a year ago and it has continued to work flawlessly since then, playing six CDs in rotation. And all the function buttons work. WD40 is harmless to electronics, so I don't think it can really do any damage. Hope this helps some members who have experienced the same problem.

 

Doing this will keep all the mechanical parts lubricated and help them function better, but the laser lens will get greasy and attract dust, which can cause disc reading errors. However, you can always take it apart and clean it if necessary.