Have had this issue for a while. Thought I fixed it with replacing REC 1, worked for approx 3 wks and has returned. Checked Rec 3 & 4, good. Checked wiring from PCB pos 2 down to FWD and REV contactors, good. Noticed burnt wiring (brown) that connects to filter 1 (blue wire on other side of filter) and wire that goes to connector on card next to analyzer port. When meter wiring showing 0.5 volts. Not sure where to go from here.