Take a closer look at the fuse slot. If you can wiggle the fuse in the slot, the terminal is broken. The u-shaped springs that grab the fuse can and do break. The result is a fuse that doesn't always make contact with the terminal. I've had two terminals do this to me (kinda expected on a 24 year old Jeep).
So the problem with a broken fuse terminal is that there is too much room. A redneck fix for a broken terminal spring is to take a little bit of aluminum foil, fold it on itself to several times so that it is no wider than the fuse blade, but folded over enough to effective "thicken" the fuse blade. Fold this little piece of thickened foil over the fuse blade (like a taco), then insert the fuse into the spot. May take a little trial and error to get the thickness right. I have done this foil trick with success, twice. Works. But definitely redneck.
Another option would be to apply solder to the fuse blade in order to thicken the blade enough to grab what remains of the fuse terminal. Again, this is a redneck repair. Good for a temporary fix. Not going to say that either way is the right way to fix it though. It is definitely the kind of fix that would make a new owner say "WTF?!"
That said, the proper way to fix a broken terminal would be to use a new ATO fuse block terminal like this:
This would require pulling the fuse box off the firewall. And if you're gonna pull the fuse block to replace one terminal, might as well replace any other one that show any signs or wear or corrosion. Myself, I haven't got around to obtaining new fuse terminals and get by with the temporary fix.