Fixed
Needed a strong light to see what I was doing.
The fix is to remove spark plug lead. The cover that sits over the plug and engine housing is held in place with a single screw - a sort of philips head. Remove and you have complete access to the switch and single lead. The body of the switch is the ground return and is made when the switch is placed back in position and the screw retainer placed back to secure the switch to the enginr casing.
Should have looked properly in the first place and cleaned the black cover and then I would have seen the retaining screw.
Alan Williams, November 2009
