Hi All. My Mk2 First Stage is bleeding air. In the diagram with the red box the air is coming out of one of the holes. It is only noticable when I put it in water (ie can't hear or feel it out of water). A bubble forms on the hole, then trickles out at rate of about 2 per second. It only comes out of one hole. I'm not sure if changing the orientation of the regulator changes the hole it comes out of. Its about 5 years old, ex-rental, lightly worked for a rental and probably never had a service. I know it didn't get a rinse every time it went for a swim, including some hot days in the sun. Grrrrrrrr. I'm not diving it and I'm not DIY-ing it. I'm interested in fault finding so I sound a bit knowledgable when I take it in for repair. Looking at the exploded diagram it seems to me the problem might be damaged a o-ring on the wide end of the piston (part 24, right hand side). Oh, and that it needs TLC in general. Any thoughts from the forum? THANKS VERY MUCH FOR ANY COMMENTS.