A while back I was having problems with my electrical system. I checked my fuse and it looked fine. I was going crazy looking for the problem.
One day my dad's friend came over and while I was under the dash, he changed my fuses and asked me to check my problems...they were all gone. I looked at the fuse and sure enough the ends (where it contacts) were erroded. Simple 10cents fix that I overlooked.
Bottom line. Change the fuse first even if it "seems" O.K. If the old fuse is still good, use them as an emergency back up.
Sincerely,
jrmd01@yahoo.com