I just came into free ownership of a pretty decent Super Tigre 3000. One problem........It looks like it had a stripped glow thread at one time and someone drilled and tapped it to 1/8 npt and put in an insert with glow plug threads in the middle. There is also a small socket head screw next to it to keep it from turning out (I think). I found the threads of the insert bubbling after-run oil and removed it. The threads seemed a little sloppy meshing. They had a little play in them until it locked down. I cleaned the threads and smeared some blue thread locker on it and reinstalled it. It still leaked a few days later.

What should I use on the insert to seal it permanently? I have some RTV silicone I was going to try next. Would pipe joint compound or teflon tape be better?