TromboneChat

Yeah, I know that title make no sense, but on my model 1 Lawler I have to align the bell at a 270 degree angle, then tighten the nut as tight as I can before rotating the bell into normal position in order to keep it from coming loose at first . But after I play for a couple hours, the thread gets so tight that I almost need pliers to loosen the nut. The Lawler has a smooth finish to the outside of the nut, so it is hard to get a good grip on it to loosen.

So is there some substance can apply to the threads that would hold it tight without making it really hard to loosen by hand?

You might get one of those strap wrenches just in case you actually do feel the urge to use pliers or God forbid vice grips. The strap is usually smooth but tacky rubber, and will grip and wont scar or deform the nut.

I think you're talking about the tenon, receiver, and nut? At first I thought maybe it was the screw bell threads since it's a Lawler.
If you're having to do all of that, the tenon taper isn't fitting properly. That's the problem, not the nut's threads. The taper should hold it in position just like a friction fit would... and the nut is only for safety. You need to determine why, and fix the actual problem. You're only seeing a symptom.

Probably one side of the taper is bottoming out which keeps it from developing the necessary friction of a taper fit. You may need to file down one end or the other just a little... or let a tech do that. Or see if Lawler will take care of it.

Well I emailed Roy and he said that most likely the brass in the receiver had worn a bit and the tenon needed to be shortened. He said he would fix it for me for free. If you don't have a Lawler yet, I suggest that you go buy one as soon as possible.