If OEM isn't a big deal here, and you don't mind a different type key, you can get one for a 1968+ ss12 and use it. I would first try carefully opening the one you have and clean it. Careful, lots of little parts.
Use a sharpie to mark orientation of the bottom plate to the case. While you have it open, check to make sure the terminals are making good connection, solder if you have to. We did this to Ryan's, works just fine. Don't bend the pot metal any more than necessary.
Thanks MH81. I had one of my techs take the switch apart today and he cleaned it and tried to put it back together. He sent it home in a vise so I could JB weld the band back around it. I hope that works.
Hey Dan I will be starting a thread on the MF10 Ign system due to a problem I have.
My ignition switch kinda went poof and something else went sizzle. I had an old snapper in the yard with the same switch, 5 pin so I checked it out against the old one and looked exactly the same. The switch works and the spring return on the start side works also. So If you have an old snapper 5 pin , you may have your replacement. My problem now goes deeper and Im not sure why so
I'll leave you with that and head to a new post.
I know that sometimes corrosion can build up at the riveted connection on the back plate of the switch. I have an MF8 switch and I assume they are the same. You can clean up the area and solder it to make sure you have a connection.
I had my tech take the ign switch apart and clean it. It now starts the motor but the amp gauge won't show charge and the switch wont shut it off. I have the motor out the the GT and I have the switch solinoid rectifier motor all grounded. It still will not show a charge. I am using a new car battery and I know it is charged but it still should show some charge. I have 2 rectifiers and tried them both. I don't want to put the motor in if I have to tear into the charging system after I paint it. Any ideas?
A lot of those switches had a copper bar/strip that goes from the case to a contact with no spade on it. This was how the ground was routed thru the switch from where it mounted. Look for the copper strip and use a probe to supply that with a ground, then turn off the key, engine should shut down. I will see if I can find a pic of what I'm talking about
EDIT: This isn't a Massey switch, but it shows the ground strip at the 12 o'clock position.
There is no M, mine has B D S C. D is the one that goes to the engine cut off and no there is not continuity to ground from that terminal. When we tested the switch I wondered how it was going to kill the motor that way. I guess I am going to have to bite the bullet and buy a new switch.
I have a new problem with the switch. Does any body know if the terminal marked C is switched? I tested the switch without anything hooked up to it and that terminal was switched. I used that terminal to turn my solenoid on and off for the power lift. When I hooked it all up the power lift works with the ignition switch off, it should not do this. The same terminal on the switch goes to the center pin of the rectifier. I pulled all the wires off the switch and checked it again and C is switched but when I put the wires back on that terminal is hot all the time. I have looked my wiring over and can't find a problem. So I am at a loss for now. I will check on it some more tomorrow night.