I took the top off the keyboard. The on/off switch, just like all the other switches, is a hermetically sealed bubble switch. Inside the bubble, which cannot be removed, are carbon contacts that make and break with the PC board the switch if mounted upon. No contact cleaner in the world would clean this, mainly because it is completely sealed. However, the contact cleaner does improve electrical contact, especially on the surrounding PC board. Thank goodness it didn't come in contact with the other boards that operate on micro-volts. This could have been disastrous. I cleaned off the PC board with denatured alcohol and a Q-tip, and now I'm back to where I was. Gonna take the board to my tech guy tomorrow and have him replace the switch. Everything else on the keyboards works just fine - no underlying problems, Donny.

Gary