Registration button #1 and #2 do not properly activate when pressed. Sometimes when one of these buttons are pressed, the corresponding led does not light & the KB does not respond to the parameters stored for that button. The button needs to be depressed a 2nd time. This is becoming a nuisance as sometimes this buttons need to be depressed without taking a lot of time to insure proper reaction. It seems that since these buttons are used in all my songs, they are starting the wear out. My KB is PSRS750 purchased in 2013. I am not a play everyday player. Help!