Yep you most likely have regulator creep from leaking o-rings, allowing reservoir pressure to bypass the regulator and prevent your puppet valve from fully opening for each shot. Do not try increasing hammer spring tension or you will risk breaking your valve stem.
You probably need to clean your air reservoir, any mineral deposits and corrosion for moisture, replace the outer o-rings and re-grease in your regulator assembly. Replace any o-rings that appeared to have taken a permanent compression set. Usually the outer ones take the brunt of the reservoir pressure.
It's pretty easy to do so try not to get to worked up about it. There are some good videos on YouTube for this. You should take the time to do at least a quick polish of some surfaces of the regulator mechanism, easily done without changing the regulator set point screw. And you definitely want to inspect the plastic nose of the regulator piston valve seat for debris or excessive indentation. See photos in the following threads for examples.
Here are some photos of the regulator from my Leshiy classic. There is more than one regulator style made over the years. Knowing which o-rings to buy is the first hurdle .
View attachment 398722 View attachment 398723 View attachment 398724 View attachment 398725 View attachment 398726 View attachment 398727 View attachment 398728 Here is another thread about regulator creep for a different gun. I contributed some experience from my Leshiy classic:
https://www.airgunnation.com/threads/maybe-i-can-fix-this-reg.1276665/#post-1350320 And here is a story of regulator overhaul for my larger Edgun R5M with annotated photos. Hope they help you and others.
Hello all, I thought I'd take a moment to share a story of a surprise failure of my 3yr old Edgun R5m in .25 caliber. I originally tuned this gun to shoot JSB 25.4 gr at 875 fps (54 clicks CCW from full CW, for those of you who have worked on Edguns), where it has performed beautifully until the...
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Good luck with your repairs.
Feinwerk
