A suggestion:

Remove the old fuse, burnish the contacts in the fuse box (using either a nonconductive material, or disconnect the battery first) and install a brand new fuse. Don't let the appearance of the old fuse lull you into a sense of security. They can go bad without completely failing. If you have the time and a few bucks, it wouldn't be a bad idea to burnish all of the contacts in the fuse box and replace ALL fuses as a preventative measure.