Don't knock yourself, there's nothing dumb about finding a loose fuse. We've had 5 Volvo 240's and all of the (not too many) no start problems have either been loose or corroded fuses, or the fuel pump relay. If that fuse just jiggled out of the clips, I'd go in and bend the clips a little tighter. It's a good idea to clean all the fuse clips and fuses, make sure they are all tight, and smear a little silicone greae on them. You'll have much better reliability then. Volvos are pretty well made but there are some problem areas which this brickboard can teach you about. I'd also highly recommend resoldering the fuel relay, don't wait for it to give trouble.