Pottered about with it this morning. Cleaned the manifold sensor, topped up the oil and windscreen washer bottle, had a fiddle with the drop arm ball joint. I only replaced it in the summer yet it seemed to have got some movement already. On releasing the circlip and cap it appeared that the Britpart spring had squashed flat. It's not made of anything springy, it's just a twist of wire. I retrived the old spring from the shed which was the correct length and jacked that in. Nice and tight now. Then I washed the car, as we middle aged people are supposed to do on Sunday.