My first reg was a Mares Abyss (MR22 1st?) bought 2nd hand, probably early 90s vintage. I had it rebuilt because it looked well used. After a couple hundred dives it began leaking then in a dive or two went to modest free flow. The HP seat had broken off a chunk that just extended to the orofice contact. I'd be curious to know more about the prospects for lung damage from HP seat failure.
What kind of lung damage happens? Like a puncture? Coz if a reg free flows I can simply ascend in due time. Unless your talking about partial lung damage from something else that builds up over time?