Looks like at some point...the venturi adjustment knob...may have been dropped/bumped/hit...with enough force to deform the plastic/graphite end and damage the S/S barrel...
Check the second stage body on the left side where the venturi end protrudes through the body...the reg may have been hit hard enough to crack the body at the venturi hole...
~snip~
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Looks like impact damage to me too... I've seen this on a few Sea Hornet Command Air second stages when either a careless diver or well-meaning deckie picks up a tank quickly with the reg attached, the second stage swings in an arc and strikes the nearest object quite hard... sometimes enough to bend the metal adjust shaft!
Used to be an even bigger problem back in the day when those welded stainless steel combo gauge protectors were all the rage, someone in a cramped boat turning round quickly with unsecured hoses could smash a mask or nearly take your teeth out with the cage