My neighbor gave me this rifle in parts, & I'm certain they're all there. He took it apart to repair & couldn't find parts. I've searched all over the net & can't find any parts for it. What I need are 2 O rings for valve assembly, & the valve (valve stem) that goes in valve assembly. I've come to the conclusion all other parts are gtg by watching a YouTube video. This is a cheap rifle, & I'm ready to toss it unless I can get a new valve & O rings. Any ideas?