There used to be a mod available for the JD-800 where you could add a trim pot to adjust the aftertouch sensitivity, and thereby restore the aftertouch function (assuming loss of sensitivity is all that's wrong with it). Gwydion Elderwyn used to have it on his Web pages, but those are all dead now. I'm trying to track down a copy of it.
Switches, knobs, buttons, LEDs, LCD screens, monitors, keys, mice, jacks, sockets. Now two joysticks!