I have a craftsmen riding mower with a Kohler engine. Model number Cv624s. stripped it down to do a head gasket job I put it all back together and now my rocker arms keep slipping off. I’ve made sure that they are gapped correctly the intake at .004 and exhaust at .006 with the piston at the top. it does not seem to matter as soon as I turn the key they seem to just slip off. I’ve looked at manuals to see if I am missing a piece and it does not appear I am. I’m hoping somebody in the forums here has run into a similar problem and can guide me out of this pickle. if you have any suggestions to help I would be much appreciated.