Thanks a lot guys, I kind of feel like the horse's ass now...
I DID say I was a newbie!
Yeah, the lever has something to do with positioning a shell on the lifter. I reassembled the rifle and it worked flawlessly...
I guess what threw me off was I had bought two identical rifles NIB, and one worked and one didn't.
I modified the poorly loading one's loading gate so badly I ordered another gate from Steves Gunz. After filing it down to fit, it actually woks better than the factory gate on the first rifle.
Thanks for all your replies and your help!
Gabriel