The separator clutch draws considerable current so any weak connections or components will make trouble. I have had to replace portions of the fuse block because of loose rivets. I have had to replace switches. I have had to crimp new connectors on the wire that goes to the separator clutch brush holder. The brush assembly and the clutch itself do not seem to create nearly as much trouble as all the wiring. If nothing is obvious by looking, get a good volt meter and a long piece of wire with alligator clips. Set the meter on its most sensitive voltage scale. Clip the + of the meter to the + on the battery and get up in the cab. Start engine and seperator and poke the - on the meter into the terminals, starting with fuse block and working up to the switch, and then (very carefully) to the brusholder on the clutch if need be. Once the meter goes above a volt or so you've found the problem. Steve in MN