gymsurely wrote:
It looks like the problem is IC501 (TDA8172). Does this make sense? The
picture returns to normal if I tap the part. I'm not an electronics
person but I'm tempted to buy a part and replace it.

i recall repairing a kv27ex about 3 years ago with this condition.
there was a geometry daughterboard at the rear of the main pcb which
had dry joints where it joined the main pcb. I also cleaned all the
pots on it to be sure.

hope this helps, Ben