Any ideas? When I play, the sound/touch suddenly becomes dull and loses its brightness and warmth.

Usually if I change voices, or go eg from R1 to R2, or press a Panel Memory, it gets restored - but not always.

The Sequencer slider is up on full, and the light next to it stays lit. Happens whether Sequencer Play button is off or even when I'm in Sequencer too. And if recording in Realtime Record you can hear the point at which the sound changes. Yet previous recordings made when there was no problem can still play OK, even when the dullness has kicked in on the live playing Touch . )

Could it be dust inside? Or is there some type of software conflict? Or contacts/circuit just worn out?

I desperately need to record some accompaniments for my choir (we do all sorts of music) and have even been wondering if it's time to get another keyboard (kn7000 or Tyros 4, though very expensive! But would prefer to get my trusty 6500 working again !
(Incidentally, I've just tried clicking the links to repairer Mike Barden's site and that comes up as Error - does anyone know if he's still operating?)

Any ideas would be gratefully received !!!!