Replaced TC40H245P with 74HC245 and all keys now working.
Cold DVM-D test of the old 245, to either supply pin, showed no forward
drop in any direction, to the gates used by D5,D6,D7 unlike to the other
pins.
Some of the front panel switches came back to life but switches 1 to 8
of 16 bank, no function or Midi LED flash. Hopefully just failed
"ribbon" 33 yearold age hardened copper wire that gave up the ghost with
all this unaccostomed flexing of connecting and disconnecting the main pcb.