Paul: I would disconnect the positive lead terminal from the battery on the mower, then follow the positive lead to the starter solenoid. Check the connection there for security (is it clean and tight?). Then the connections on the starter... disconnect, clean and tighten them. remove the terminal from the negative battery pole, and remove the ground cable from the frame of the machine, clean the terminal and the point where the negative cable contacts the frame of the machine... do the same for each battery terminal and cable terminal. Connect the negative battery terminal last. Your problems should be solved.
