My engine's decided to stop turning over - it's not just a flat battery, as I first suspected, nor is it the relay, as I've tried a new one (the car's been re-wired to use a relay rather than just through the ignition switch). The motor isn't seized, so I figure it has to be either the starter motor or the ignition switch. There was no gradual break down, one minute it was working, the next it wasn't.
When I turn the key to start, the relay does click, so I'm leaning towards the starter motor. However I've heard that the ignition switch can die - I'm going to probe around with a multimeter tonight to see if it's making good contacts. How do you remove the ignition barrel from the steering column? It has two regular screws, but also two grub screws with no head, is there a trick, or do I need to drill them out? I guess I could cut a straight slot in them with the dremel...
I've probed the connections to the started, it has 12V, GND, and a third connection that briefly gets some volts on it when I turn the key to start (less than a second, hard to measure). I'm guessing this is the signal that engages the solenoid? Shouldn't it be constant voltage when the key is at "start"?