Mostly switches. There have been a few that have had problems with a large connector that is located in front of the battery box, and is exposed to water in heavy rain. I guess you have to remove a lot of stuff to get to it.
You mean the "frangible link" as we used to call it on cars? They call it the "main fuse". 55amp. The ends where the screws secure the fuse are apt to corrode with moisture. I added electrical connection compound on the ends and the screws then sealed the whole thing up with "liquid electrical tape". No more problem. You can cut the rubbery stuff with a knife if you need to replace the fuse.
Another common problem is the main ground on the back of the engine block. Run another one to the steel frame. I also added another ground strap between the engine & frame.
Also - do the relay-headlight upgrade mod, to prevent failure of your starter switch. Bonus, you can use a much higher watt bulb for the main headlight. I've been using a 130/90 for 15 years. If you go that big, also get a high capacity plug for the bulb.
