My Pietta 1851 Navy wiggles a little

[Doug.38PR]

My 1851 Pietta wiggles a little.  That is the cylinder rod rocks just a hair....but seems in no danger of falling off.
Years ago I unscrewed it from the frame so I could clean the inside easier and screwed it back in.  Now I can't screw it off or tighten it (not sure why).  I took it to a gunsmith in Houston years ago and he didn't seem to think anything was wrong and didn't seem to think it could get any tighter than that.

Any thoughts on this?

[Flint]

There should be a locking pin drilled into the edge of the arbor from the rear. (See exploded parts drawings on VTIgunparts website).  This would prevent rotation intil the pin is drilled out.   (If it's a brass frame, it may not have one)  Whenever I have removed an arbor, I have replaced the pin with a #6 setscrew by threading the hole.  The next time you disassemble that part it is much easier.  Locktite will stop the wiggle, but attach the barrel while it sets up so it is locked up aligned.

[Coffinmaker]

Plus 1 to Flint. 

Addendum.  If the barrel assembly doesn't move with the wedge in snug, you an also leave it alone.  Sp long as the barrel doesn't move, it's a non issue.

Coffinmaker