Has anybody else experienced this with the 555? My 2, 3 and 4 buttons lost their velocity control. I have to press these buttons extra hard in order to get them to play. All of the other buttons work perfectly fine. This just happened unexpectedly after using the 555 flawlessly for months. Any advice?

my two button is a little "finiky", but i figured it was just from bangin.

I called Roland today and they said I could drop off the 555 for service. Any ideas of how much something like this would cost to fix? BTW its out of warranty.