Fuses are made with a bismuth alloy that sometimes corrodes in a humid atmosphere.  Not much you can do about it except replacement.  The corrosion is almost invisible, but is sometimes seen as a slight whitening of the fuse element inside the plastic.

A general tightening of ALL electrical connections from the battery to the starter solenoid may be in order, especially where nuts and bolts are the connector types.  Multiple pin connectors (Molex style) sometimes respond to taking them apart and then reassembling.  The attendant abrasion cleans the contacts.  While you do this examine them for "pushed" pins on both sides of each connector.

Good luck, intermittent electrical problems are a bugaboo.  Maybe try to find an owner's web site where someone else has found the reason and a cure.

Ray Nielsen, in Minneapolis.

With the bike running safely at your home, Wiggle some wires (batt connections, wires on either side of the main fuse, etc) to see if it suddenly quits. Wiggle the main fuse without pulling it out of the fuse box.

I like to clean electrical connections with a bit of scotch-brite pad and a spritz of electrical contact cleaner.

Ride the bike locally till it warms up. Then return to your house and shut it off for 10 minutes. If it re-starts, ride a bit more and hit a few small potholes. Return home for the re-start routine. If the bike re-starts reliably, ride it where you want.

If the bike fails as before, leave the key "on" and wiggle wires til it lights up. You may find that a batt connection has to be slightly loosened to wiggle a wire to make the bike light up again.

A 12V continuity light might be fun to have. Get a budd to show you how it works so that you can test connections for yourself.

Motorcycles! Making mechanics out of riders since the late 1800's.

Keep us informed of how it goes for you.

nobody rides half as well as they know how.