For some reason the hinges on our back door are beginning to perish to such an extent that one of the lower hinges (there are 4 in total - it's a half door) has broken in two. I want to replace all of them before they all snap. However, the screws that are on the doorframe part of the hinge are refusing to budge. (The screws that are on the door itself are moving fine). I would guess that they were put in with an electric screwdriver and may have been over-screwed as there seems to be no grip at all with my humble hand held screwdriver. I've given all the hinges a spray with WD40 but the screws in the frame refuse to budge. Any tips on getting around this problem?