Dealing with similar issues on my .22 cal flash (QE US version). Had it for 5 trouble free years, then one day while shooting it suddenly started hissing and lost all pressure. Wouldn't take a fill, pulled the cylinder out and found it was leaking near the valve pin.
Disassembled, cleaned, and lubed everything and it took air, worked for a few weeks and then started acting up again. Would suddenly start dumping all pressure in the middle of shooting again.
Reached out to Hatsan and got a replacement valve pin and valve seat, installed them last night, filled it, and woke up this morning and it lost 50 bar over night. I think I may have chipped the o-ring on the valve seat while "seating" it.
Thankfully these guns are super simple to work on, I can have it fully disassembled in 5 minutes now that I've done it multiple times.
Is there a proper procedure for setting the valve seat into place? I've just been using a 4mm T-handle Allen wrench and pushing until I feel it "pop" into position. I am also putting a light coat of food grade silicone grease on the o-ring. Also, does anyone know the proper o-ring size that goes around the white plastic valve seat? I'm going to need a replacement since I think I damaged this one.
Sorry to hijack the thread, but I figure my issue is on topic. Thanks!
Figured I'd include a pic of my flash, absolutely love this gun, want to get it back in order!
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