custom 2400kt co2 carbine won't hold gas over a few hours

I just received a custom 2400kt with Walther 14.6" barrel in .177 caliber. Ordered it as gift for my uncle.

Loaded a caplet of co2 and fired 3 test shots. Put away until later testing. About a day later I found it was totally out of gas. I had used pellgun oil on tip of caplet and hand tightened cap as per instructions. One day. So I loaded a new caplet and shot over a chrony using RWS 7 gr hobby pellets. 599, 613, 607, 636, 634, 624... for six shots until I got interrupted. EXACTLY 12 hours later I resumed testing and first shot got Err on the chrony screen and sounded very weak. Finally read 389 ft/sec and then 322 and then 241 ft/sec. Barely pooped that last one out!

Anyone know of a fix for this obviously leaky new gun? If there is someway to correct it without sending it back I want to do it because I want to give it to my uncle soon. Thank you in advance for any help you can give me!  

  Wcwiseman  

You might need a new seal, an inexpensive part, but requires dis-assembly.

These guns are easy to work on, and schematics are down-loadable from Crosman's website.

Another thought - the valve retention screw head to screw hole fit is sloppy on all the 22XX series . I re-tapped the hole to 8-32 and use a Discovery valve retention screw. It secures the valve better and makes for a better valve/cart mating -

Have fun, learn, and repair away!

Vines