Hi: In addition to getting the door open (see other thread) my first objective was to hook up a battery and see how bad things were electrically. Good news, there was no smoke, bad news, there was nothing else either. Traced +12 to the ignition switch but nothing was coming out in any key position. So, it looked like that would be my first parts order. But then figuring I had nothing to loose (except small springs, etc.) I decided to pop it open to see what could be accomplished. Turns out, a lot and I'm happy to report all circuits are up and running, including solenoid and starter!
I've been away from British forums for some time, and imagine that restoring these types of switches may have been written up elsewhere, but I found a little trick and thought I'd share for future reference.
1) Put the body lightly in a vise and tap out the edge crimps with a small screw driver and hammer. Photo 1
2) Once loose, the back of the unit (with lugs) will rise up about an 1/8 of an inch due to internal springs. Make sure the unit is facing up so nothing falls out.
3) The guts consist of several layers that all come out one at a time. Photo 2.
4) I didn't get a "before" photo, but as suspected, all contacts were messed up with a combination of solidified grease, green corrosion and a few burnt spots to boot. Cleaning and polishing results are in Photo 3.
5) Now, how to reassemble? The white "body" goes in first, but there is a catch in that the detent function happens between this part and the bottom of the case. In Photo 4, you can see the detent spring in it's hole, and the ball bearing in the the most clockwise dimple (Key Off position) A dab of grease will keep these both in place.
6) So you have to orient the white body so that when you insert it, the spring in hole covers the ball bearing. This means the white body won't fully seat unless you apply pressure to compress the spring. Not that hard to do after some practice, but then what? You still have three more layers (and more springs) to pile on top and I had no luck doing this without the detent arrangement losing position.
7) I figured the factory must have had some sort of fixture and then it occurred to me that what was needed was a hands-free way to keep the white body in place. And since this part is exposed at both ends of the unit, it looked possible to drill a hole through it and use a long, thin screw and nut as an internal "clamp" This also provided a convenient handle to put in the vise during the remainder of assembly Photo 5.
8 - The sequence now was to replace the three springs (taken out early on to prevent losing them) Then the 3-contact brass rotor, which just floats on the three springs. Next comes the slotted insulator and finally the back cover with lugs. Oh, and a good amount of dielectric grease along the way.
9) Due to the three springs, it's still a bit tricky to line up all the layers over the center of the white body, but without too many tries I was able to get to where I could push down on the back cover and get it to fully seat in the case. A helper came in handy to maintain pressure with an open pair of pliers while I tapped the crimps back in place.
And that was it. It probably wont last for another 50 years, but then again, I'm not exactly going to be giving it much of a workout anytime soon.
Ron