Buy a couple of cans of freon used to clean camera's (FREON, not just compressed air).
Turn can upside down so that liquid comes out instead of just air.
Spray liquid onto the glow plug where the the GP goes into the head, and spray the area around the hole. This will make the hole get slightly larger, and will shrink the size of the GP.
You may have to hit each GP with a couple of cans of freon each.
If really helps a stuck GP, and is far easier then pulling the heads.
Turn can upside down so that liquid comes out instead of just air.
Spray liquid onto the glow plug where the the GP goes into the head, and spray the area around the hole. This will make the hole get slightly larger, and will shrink the size of the GP.
You may have to hit each GP with a couple of cans of freon each.
If really helps a stuck GP, and is far easier then pulling the heads.