Hi Norm, You don't say what model it is, so I presume it's 1980/81 which uses a 3 position/5 pin 103990 Ign Switch. I've handed my C-120 Info on to Roly with the Tractor, but checked for comparison using parts list.
This diagram should be identical for you to check yours-
The solenoid may look non serviceable, but I only needs 4 rivets drilling out and replacing after a clean out. Covered it in my C-120/Raider update if you want a link?.
Hope it helps.
Edit - 103990 switch pins are marked-
S- Safety Switch/ Sol Start. R- Rectifier. A- Accessories (lights). I - Igntion (poss via seat safety switch) . B - Battery/Ammeter .