I've come across a couple of DITY techniques:
1. resolder all connections using a high grade electronics flux and then clean using deionized water and use compressed air to blow dry.
2. Replace the LM-2901 comparator chip and the DUAL gate N-channel FET. Both are available at Radio Shack.
3. Buy a rebuild from this board (that's my choice).
Best of Luck. And let us know how it works out. and what you all found.
S, J.R. Brown
1986 280GE LWB Anthracite
1980 450SEL Champange
1981 Volvo 240DL UPS Brown