Taipan Original vet leak

You should replace them all and be done. Order another kit for the next time which should be in 5 plus years.

How about that one? Looks like that’s an o-ring. I wouldn’t think it’d be by the gauge as there’s not much movement there.

Marc, I’m not a vet guy as you know, but in my experience slow leaks that just come on suddenly are typically at the fill port. If using a probe, sometimes we transfer a tiny dash of debris on the probe that gets into the check valve once you open up your tank valve.

Or, the check valve within just needs some lube as it’s probably not seating tight after a top off. I’m working on an mk2 wildcat now that suffered that same problem. Opened up the check valve, cleaned everything off, and fresh silicone grease and all fixed.
Before opening up the gun, what I would try first is drizzle two to three drops of silicone oil into your tanks fill hose before you connect it to the gun. When you open up the tanks valve to air up your gun the HPA will inject that lube into the gun and the leak if coming from the check valve should stop.

The rest of your o rings down stream within your air tube will appreciate this douse of lube, too. Any excess just gets shot out the barrel

IMO ... the #1 leak spot is the air tube fitting that goes into receiver ( O-ring that surrounds poppet seat )
But at 5 years ... they ALL ( O-rings ) need replacement & regulator serviced too.

Yup, thats the one that typically gives up first.

A buddy gave me his 5 year old Vet last winter (same problem as you), and with a lot of PM help with Franklink, I got a list of all the O-rings and replaced all of them. I'd never had taken an airgun apart before, but managed to do the job correctly.

In Jairow's post, seems to me, the red arrow pointing to the O-ring was the most deformed of all of them. I think I bought at least a dozen of each size needed for a complete re-seal. If you need additional O-rings you don't have, send me a message

Just had to replace that oring on my Ukraine Vetty. Super easy. I have three Veteran now and ordered enough orings to rebuild whole gun 6 times for less than thirty dollars delivered.
The Oring store has them all.
Super service and awesome staff.

If need to check certain areas for leaks, I use an eye dropper with soapy water to put it right where you need it and with the least amount of bubbles to start with.

I had a constant, very slow leak on one of my veterans, even after all orings replaced and reg rebuild.

I keep a spray bottle with a fairly heavy mixture of water and Dawn dish liquid on hand, it works pretty well as a leak finder.

Spraying with soapy water showed a tiny leak at the gauge to fill adapter interface. Replaced the gauge oring a couple times to no avail.

Installed the gauge in a test fitting where I could clearly see the vent on the back of the gauge. Sprayed that area and bubbles slowly appeared at the gauge's vent port...

Ordered a replacement gauge from Talontunes, problem solved.

Yea seen a few leaking gauges over the years. Bourdon tube solder failures most likely cause.

Going to leave this here in hopes it can help somebody if they find this discussion at some future point.