I had a problem with the rear lights (tail lights, number plate and boot lid) whereby all worked correctly with the main master switch in the first position (side lights), but when I switched to the second position (full beam) they all went out! The first thing I did was to check the current at the fuses to see which side the problem was coming from.
When switching from the first position to the second position, current at the fuses disappeared so at least I knew which side to check next. I was working alone and from inside the car I couldn't see the rear lights, so in the absence of a mirror, I wired a meter to the boot lid light and placed it on the rear window so I could see the swing of the meter from inside the car.
I then set about checking the main switch connections itself and as I started pushing the wires at the back about, the meter registered current so I'd found the problem quite easily (luckily for me as electrical problems can be a nightmare). I removed the switch and cleaned the contacts up and, bingo, the rear lights were now working correctly.
Next on the agenda was to sort out the rearview mirror. When I drove the car home from buying it, I couldn't see much in the mirror as there was a lot of vibration due to someone having put an extension piece in which wobbled about. It turned out they had done this as the thread where the mirror screws into the support was completely stripped up until part way down, so the extension piece was able to go further to bite into good thread. I took the mirror and support to the local garage where they kindly repaired the thread using a HeliCoil® insert.
I now have to track down the missing piece that screws into the support and presses against the window to increase the mirror stability.
The last little job was to replace a dirty air filter with a new one (the orange one is the old one):