I love these old beasts, but all the help I can give is my experience that the Cub Cadet switches and wiring are crap and will always give problems. There are those here who will advise one to keep replacing the crap as is fails; good on yer. Yes, the myriad lawyer interlocks are safer than not having them in place; however, the safest mower is the one which won't start or engage the mower deck; what a safety feature that is!
I owned two of these and to keep them running over the ten years I worked them, I ultimately rewired both machines so there were only two switches: Off/On/Momentary Start and an Off/On for the PTO. I'm not suggesting anyone do this, but it was the only way I could keep my two machines reliably starting and operating.
jack vines