The red kill switch is held in by an E clip on the underside of the switch. Be careful removing this as there is a small spring and ball (real small) under the switch which can go flying. Clean everything well and check that the lead contacts on the switch terminals aren't shorted together. This can happen because the current load can soften the solder and bridge the gap between terminals.
Best to use either a marine grease or silicone vacuum grease to lube the switch.
-P.