I've been meaning to take it to bits and fix it. So, having chosen my time carefully, at 11:30 pm last night I took the darned thing to bits. And now it is completely broken. So today I have just nipped out and bought another shaver. This one is very posh, and can be washed under the tap (although the instructions suggest that you don't have it plugged into the mains at the time).
It seems to work fine. I now have a face as smooth as a middle aged babie's bottom.