went to site today checked jack wiring and it was as you said black to positive next i noted the voltage it was 20.5 v maybe little low but long run 400' (approx.)than i swapped out the cords ,and finally changed out the 7324 set and after each time still the same problem ! but the only time the line keys did not change back to default position was when i only connected the 7324 and not the cap set ..still open to suggestions