Complete gear was new 4 years ago. Used only ones for 45 mins...
Thanks for the input. I'll have a pro look at it.
Adjustment? How? I should probably just get the complete kit to a service dude.
Trying to learn as I go, what causes this?
If this is true, it may or may not need a complete service which includes rebuilding the first stage and both second stages. If this is a LX model, and it's leaking but the octo is not, it's very unlikely to be a first stage IP issue. That's because the LX 2nd stage is balanced, and as such less vulnerable to IP fluctuations than an unbalanced 2nd stage, which is likely what the octo is.
The problem with going to a "service dude" is finding one that is competent. They're out there but so are the hacks. As soon as you say "4 yrs old", the shop will say "complete rebuild." Which is fine as long as A)they can do it without screwing up and B)you don't mind spending the $150 or so it's likely to cost.
If you really want to learn about this and you're mechanically inclined, get the Vance Harlow book on regulator repair and start reading. If that piques your interest you can probably fix this reg easily.
If it was my reg, I would start by confirming that the IP is steady and in the right range. That takes an IP gauge which can attach to the LP inflator hose. I bet your IP is fine, but you really need to check that first. Then I'd simply adjust the seat/orifice on the 2nd stage to stop the flow, or possibly replace the seat. What usually causes the slight flow that you're having is the fact that when the reg is in storage, there's some light spring pressure on the 2nd stage soft seat, pushing it against the hard orifice, which causes an imprint in the seat over time and degrades the air-tight seal. So, sometimes it's as simple as tightening the orifice a bit, sometimes you need a new seat. One possible reason it's happening with the primary 2nd and not the octo is that usually the primary 2nd is adjusted more lightly for easy cracking effort; this means that with some wear, the seat is more prone to leaking.
If it was not stored well, like used once in salt water, not rinsed or soaked well, and then left to sit for 4 yrs, it could really be in rough shape. If it was used once in clean fresh water, rinsed, dried, and stored correctly, it could be in like new condition except for this simple adjustment. You don't really know until you look at it.
---------- Post added January 24th, 2013 at 09:52 AM ----------
There are a lot of potential reasons.
Most regulators have valve seats that keep pressure on the diaphragm that is in your 2nd stage. This creates a crease in the neoprene, so when you fire it up, that crease is still there. It gets worse with time. It is way worse if you've stored this reg in your garage (heat is the culprit). Remember, you have seals inside your 1st stage, too.
Regardless of how often you used it, time is the culprit, here (and lack-of-use). The LX is a good, fully balanced reg. If you bought it new from a dive shop, should have lifetime parts warranty, and all you'll have to pay is labor.
You should invest in a full service of the regulator. When those neoprene parts fail, they tend to do so in a big way.
Again with the freakin' neoprene. There's no neoprene in this or any other modern regulator. There's no pressure on the 2nd stage diaphragm in storage. There's no "crease" in the non-existant neoprene.
I hope you know more about teaching diving than regulators. You are, after all, a dive professional. No offense!
