Well, I certainly fitted a new fuse and tried to "clean" the fuse holder (scrubbed the female spade connectors with a jewelers file and tightened them with some slip-joint pliers; sprayed the connectors with Caig DeOxit/Gold, Vaseline on the spades).
On my third fuse holder, so not feeling very confident at this point. Sure, I could run a screw into it, but the screw head will be +/ hot and have to be insulated from its surroundings. I thought of using a couple wraps of electrical tape, but don't find that to be a very elegant solution . . .
Perhaps I've let my ground path get funky. One of the troubles with having one bike for so long, you may be led to think, "I fixed that already."