ORIGINAL: PrjctStrtFrce
Ya, you definitely need a new head or the under-head, depending on how your motor is set-up.
With glow plugs you just tighten, and once you feel resistance just tighten the slightest amount more and stop.
You're right I took it apart and found the under-head, so that is the good news because it's not as expensive as replacing the whole head (my wife already thinks I spend way too much money on my truck)
That's the good news. Bad news is I have to wait until next week until the LHS gets another one for me to put in.