I just got a used 10-22. I took it to the range and sometimes it just won't fire! The hammer simply doesn't fall. Then after a few pulls the hammer would finally fall and fire the gun. After the first shot fired the subsequent firings would be fine. It was always just the first shot after cocking the hammer by pulling the lever back. I've taken it apart, looked it all over/cleaned everything. I reassembled and now it won't fire at all (yes I assembled it correctly!) Are there any animations out there that show the exact engagement and release of the sear/hammer/trigger? I can't see what is going on in this thing.