In the pettifogger articles, read with particular interest the section on the shaping of the bolt leg which rides the hammer cam.
IIRC correctly, on some hammers it is possible for the cam to move and get out of position. I don't know how frequently that happens but you may want to check the photo of the cam in the article as compared with the cam on your hammer.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson