seems to me that the only way something like that could happen, would be if the sleeve wasn't seated properly. through a couple heat cycles, the sleeve moves and the glow plug loosens up.
Par has a old dealership building up in Clarks summit pa that they are working out of.
thats prolly where your going?? I can prolly get you hooked up at a nice hotel right in Cl at the ramada. Let me know when your coming??