Got the sustain to work with a simple switch externally but not with the
supplied footpedal. Looks similar but no name and slightly different
pedal shape. This one uses 2 conductive foam switch pads at top and
bottom of stroke. So varying in a somewhat undefined way from about 30
ohm to about 160 ohm. 30 ohm as rest (internal sprung)state of one and
160 ohm as fully compressed (down), as set, on the other. Resistance
changing between the 2 positions. It looks as though the P80 is on or
off sustain not variable, correct?. Removed the "160" ohm membrane and
it now works , going from 30 R to infinity, leaving the membrane stowed
inside for anyone later to play with