I've just replied to your question in your build thread. A copper washer under the head nut should do the trick.
I had a problem with a cylinder were the studs were tightened too much causing the cylinder to crack around the studs.
Copious amounts of silicone sealant in the stud holes in the cylinder and threads of the studs solved (bodged!) the problem... Don't ask me what type of silicone I used... it was over twenty years ago.