bill i hope its not a issue with that dang horn wire being pinched on the bracket lol, im sure you will find it, must be wire caught under something......
you can also get a circuit breaker with the same amp as that main fuse, so when it pops you just rest it, way better then chg fuses out, ones you get it figured out then pop a reg fuse back in its place, a little cheaper on the long run for diagnosing the issue.
good luck man
I wanna see one of those circuit breakers!