I heard of folks changing entire wiring harnesses only to find the old one was ok.
Simply by changing / checking every connection, they magically work.
x2 on the ignition switch.
I had one that wanted to be turned on and then backed off a few thousandths to get a connection.
There is a tutorial with great pix detailing the procedure if you need to take the switch apart and clean contacts.
The 1985 models have a really odd fuse that looks like a miniature end wrench and not clearly marked.
Not sure if that's it but I know they are NOT real obvious in the book and a great way to get stuck far from home.
All my 84 models got transferred to a returning vet for an asparagus farm or I'd go look.
A few of us have swapped many and all known working
parts only to get nowhere.
You guessed it, the fix was just time checking all connections.
Thankfully that doesn't cost anything but time.
Pls let us know what you find