Same problem 2005 Astra 1.9 CDTI Try the fuse first, if not that then its the micro switch come un-stuck. The URL link in this string of messages is excellent. However, instead of re-sticking the switch in I've done the following. Push the switch fully home, then drill a 1.5mm hole through the body on both sides of the tube the switch fits in, as close to the switch as you can. Carefully oval out the holes horizontally, just big enough to get a small cable tie through. Thread the cable tie right through the housing immediately above the switch but dont tighten it yet. Insert a piece of non compressible packing, I used half a match, between the cable tie and the top of the switch. Then tighten the cable tie. The packing under the cable tie provides tension to ensure the switch can't slip back. Unlike using glue, the cable tie is unlikely to degenerate with age.
Mark Pascoe, September 2012