Leaking near check valve on Yong Heng setup

[OatmealMu]

I have a check valve between the small gold filter and air tank. Today, it started leaking between the check valve and quick disconnect on the gold filter. I figured it was the o-ring on the disconnect. Sure enough, it was damaged, and I replaced it. The problem persisted, so I tried switching the filter around to use the other disconnect. Same problem. Maybe the check valve was the problem, so I opened it up and inspected the o-ring. It looked fine, so I put some silicone grease on it and reassembled it. Again, same problem.

Is it the Yong Heng? Maybe it's not making enough pressure to open the check valve. Anyone know?

Here's my setup:

 

[OatmealMu]

When in doubt, tighten things down and start replacing o-rings.

The air seemed to be coming from all over the place, so I dug into my o-ring stash and began replacing everything around the problem area. I also tightened the quick disconnects. I highly recommend the 150mm Lobtex adjustable wrench for this. It's thin enough to squeeze into tight areas that my Tekton stubbies can't reach.

In any case, I think the problem seal was the 20 x 2.5mm o-ring on the filter cap. It looked fine, but looks are deceiving. I'm just glad I didn't have to tear the compressor apart.