I am in the middle of fixing a problem with this model. My problem is that the switch won't turn. For this it is likely to be the safety lock mechanism. You need to reach in under the green knob and lever it up gently. It is held by legs with a bump. After this undo the two screws holding the top cover and remove the cover. The problem could be several things including a broken return spring. I have cleaned everything up and smoothed off the metal arm which seems to have solved the problem. Take your time to work out how the whole mechanism works before reassembling.
Hope this works for you.
Mark, May 2010
