Baby's first lift, a JLG 40H 1997 with Ford engine and 3 PQ Controls at the platform. s/n 047753030030541 All the ground controls and platform switch controls work as expected but none of the proportional controls does anything. PO says they worked intermittently and in certain positions before the lift was parked last year. Wiring appears intact and undisturbed. Any suggestions on where to start troubleshooting?
Check to make sure you're getting voltage to the proportional control dump valve. If I remember right it's located on the right side of the radiator area.