ex572 car audio speakers

I have a 1998 Ford Ranger that I've installed my old ex572's into. On the rear speakers, they keep shorting the head unit if they are tightly installed. Is there a quick fix to this, or is it going to require relocating the speakers. It seems to have just recently developed as the speakers were in for almost a year. For whatever reason, if i leave the speaker out of its intended space, no short occurs...ever. I've got a 700 mile drive coming up and i'd like to be able to use all of the speakers in my truck. Any help is appreciated