I bought a new Model 60 about half a year ago, and it's given me a lot more trouble than it has rabbits. After a month of use and about 400 rounds, the hammer slipped, and I sent it in to a gunsmith. It worked beautifully for one weekend after that, but now it's acting as a single-shot again -- only the first round will fire. The spent casings seem to eject fine, but the next round won't fire (and I feel no pressure on the trigger). Sometimes I can get it to work if I pull the bolt back slightly, but this is really a pain. I cleaned thoroughly last night, but it still won't cycle. Any thoughts on what's wrong, and how I could fix it? I appreciate any advice.