Edison-base fuses have incoming power to the center contact in the bottom of the screw shell. Often that contact is a screw that also holds the screw shell in place by means of an insulating washer. That screw must be snug. The screw shell receives power only when a good fuse is installed.

I did not notice any loose screws, I did loosen and then re-tighten the screw shell to make sure there was contact. I will recheck all the screws one more time....any others??