Howdy Siringo, without seeing it I'm going to make some guesses. As to the round getting past the carrier, that happens with some centerfire '66's when the loading gate tab bends or breaks, but since the .22 version has no loading gate obviously that ain't it. I haven't seen what a .22 carrier looks like on the inside so I don't know what the stop looks like that is built in to the carrier, but maybe it is worn? If you take it apart, take a picture of the inside of the carrier to show us. Now as to the carrier seeming to not rise far enough, sometimes that could be a weak carrier spring (the flat spring that attaches to the screw on the bottom just behind the carrier opening in the frame, on the right side of the rifle, or the left side if it is upside down) so make sure that screw is tight (or that leaf spring could be worn and need replacing). But you said it seems to be raising all the way, which you could verify by reaching underneath and pushing it up with your finger. If it is indeed all the way up, possibly the lifter arm needs to be bent a little so it raises the carrier further. When people have out-of-battery discharges, that arm and/or the lever can get bent, but I wouldn't think an OOB on a .22 would have enough force to do that. Since I don't know what the cartridge stop looks like in the .22 carrier, I'm wondering if both problems could be related, that is, the carrier is also too low when it is in the lower position. Does it stick down below the frame in the down position? I'm out of WAG's for now
Perhaps Pettifogger or Coffinmaker will see this and chime in. If nobody else knows, I'd send a PM to those guys.
Good luck.