This might have already been covered but.... My O/S indicator bulb failed (just as I started a 150 mile drive!) but I had a replacement. To replace it the cover over the LDS tank has to be removed and the bulb is in a bulbholder. The instructions are "turn the bulbholder (anticlockwise) and pull it out" (or words to that effect). This is just possble if one has small hands but a pair of pliers might be useful. I got the holder out using its lugs and replaced the bulb but, on re-locating the holder into the lamp and turning it clockwise it locked in place but wouldn't light. Next day (at home) I removed it again and realised that the lampholder will fit in three positions but only one will make contact with the supply. So - before removing the lampholder it's worth marking the top lug with something (paint if you have time to let it dry or a bit of sticky tape) so it can be replaced with the correct orientation.