Problem soved.

@ Eric: Thank you, once again. Key was knowing that the +ve wire should go to terminal 30. Once I knew that, it quickly became clear that there was something wrong with the switch. I opened it up and found lots of grease (looked like copper compound) inside, which may have turned a little hard and prevented proper contact. I cleaned it out, cleaned the contact surfaces with emery paper, re-greased with fresh copper compound, and re-assembled. Now it works 100%.

This probably explains why the key broke in the first place. What do you do when nothing happens when you turn the key to start? – you turn harder. And what happens if you turn hard enough …?.

Next I am going to install a push-button starter switch, which I have often seen recommended on the Brickboard.

Incidentally, terminal 57a is “on” in key position 0 and “off” in the others. It doesn’t seem to be used. Terminal 75 is “on” in key positions I and II, and “off” in the others. It showed signs of having had a connector connected to it earlier in its life. There was a wire coming from the cigarette lighter (item 47 in the wiring diagram) which had been left dangling. So I connected it to terminal 75. Cigarette lighter now also works.

@ Patrick: I did use a multimeter when initially trying to figure out where the wires should be connected, but I was getting strange readings (like 5Kohms in one position and open circuit in another). I should of course have realised then that there was something wrong with the switch but it didn’t cross my mind.

What I still do not understand is the statement in the handbook: “With the key in the ‘garage’ position the entire electrical system is connected up except the engine ignition system”. This can’t be right. The switched +ve (red) goes to no. 1 terminal of the fuse box, and no. 2 terminal of the fuse box goes to the ignition coil (brown wire). Inside the fuse box no. 1 and 2 terminals are bridged. So the one can’t be “off” when the other is “on”.

Simplesimon