Hey, folks, I got a cheap Marlin .22 semi-auto rifle that my dad bought for a few bucks about 20 years ago. I grew up shooting this gun and put many thousands of rounds through it. However, it has developed a problem that I don't know how to fix. It hangs up about every third or fourth shot. It doesn't completely eject the spent shell and the bolt closes on it, jamming up the whole works. Usually, the jammed shell is about halfway out and pinched up in the action when this occurs. My dad and I have both given it a thorough cleaning (even to the point of removing the bolt) and it seemed to help somewhat, but very little. Any ideas?