Possibly a duff connection on one of the board connectors. Power off, remove covers, disconnect circuit board connectors and clean with toothbrush. May help to tighten them with a pair of pliers. Clean off any corrosion or crud, refit and test. Closely inspect the entire wiring loom and circuit boards, looking particularily closely at areas where the wiring touches the machine frame. Your'e looking for any signs of wear or fraying which would allow the bare wire to contact the frame
check out www.2ndwave.co.uk/manual.html
dannyboy, October 2008