Thanks for the tip.
I will drop him a line.
I actually showed my unit to a friend who does amplifier/mixer repair....he claimed that it was probably an IC chip that went bad.

It can't be the buttons themselves as the defective ones are not grouped in any logical order or physical area.

I called Yamaha to order a replacement main board. They had it in stock but quoted an absurd $1400 or so. I kindly pointed out that the PSR2000 was available for less that that when it was current! Talk about extortion...

But if anybody thinks that they have any troubleshooting suggestions, I'm all ears.