I've seen quite a few of damaged knurlings on caps, nuts and such. There's a reason why these are common. Despite that they're supposed to be tightened solely by fingers, unscrewing them is often a different story. The captive nut often gets too tight to unscrew just by fingers. Especially when its not been opened for sometime and became stuck as residues on the threads varnished-up or when corrosion sets in. For a non-collector, marring of the knurlings is certainly the least of his concerns. A pair of vise-grips and cap would be loosened up in a jiffy. The following stuffs obviously did not catch on with these guys:- 1. A piece of leather. 2. Penetration oil.
Sometimes the damage was caused by the uninitiated tighten the collars down on to buggered seals. I suppose, all in all, it’s part of the lantern’s history and sometimes history is not pleasant. Cheers Pete
