F# and C on my Yamaha psre363 stopped working, on every single octave. They will play after a while and stop after a while. I had the same problem with Eb and A but I haven't had it for a few weeks now. I tried the slapping methods and hair dryer methods. Slapping didn't work and the hair dryer melted some keys together so I had to swap them with another keyboard I had laying around. Any other methods before I open up or replace my keyboard?