It sounds like dust or another foreign object under the keys. Try with an airspray to blow it away.
Maybe you do, but a good practice is to cover your keyboard when not in use with a dustcover.
Hope this solves the problem.
Oct 16, 2009 Rating
Keys won't work.....solution by: Anonymous
I have a psr 520 and had it stored away for some time and when I tried to play it the same thing happened. I don't know how mechanical you are but I opened the unit and the key contacts can be unclipped from the keys after you open the unit.
( no screws) When I carefully turned the green board over I wiped it down with some phillips dvd cleaning fluid and a white cd cloth and clipped it back in and it plays fine now. Hope this helps....
