That's too bad. Have you gone up to a 3/8ths or even a 25/64ths? A 13/32nds might be just a hair too much. All the threads of the glow plug are removed and the center heating element has been drilled out? Man, I really hate to see you have to go the head removal route if that glow plug can be accessed with a drill.

Again, good luck. We're thinking of you and hoping for the best.

Len