There is a thin, hard flat washer between the hammer spring and the hammer adjuster "screw cap". I have seen this thin washer crack into two or three pieces and then these small pieces fall down to interfere with the cocking/trigger assembly. It is very easy to verify. Just remove the rifle stock and then take a bright flashlight and look into the trigger assembly from the rifle bottom. If you see anything odd, any pieces that look like they do not belong there, it is most likely a piece of the washer just mentioned. If you do not see anything odd and you are mechanically inclined, consider removing the trigger assembly to verify there are no washer pieces present. There are only 3 pins holding the trigger assembly in place and it is a very simple trigger design; to work on clean, lube and reinstall.