There are several things you might check before taking the starter out. First I would get the battery tested and replace the fusible links as PM if they have not been replaced lately. I chased a no start issue off and on for about a year. with mine I would turn the key and hear a click but no start. sometimes tapping on the starter with a hammer while turning the key would help, sometimes not. It only stranded me once.
I replaced the fusible links, rebuilt the starter, replaced the starter, replaced the ground to the starter, replaced/upgraded the large power wire to the starter, replaced the good battery with a better Sears marine battery and still had intermittent no starts. After some research I found that the starter logic circuit that runs through the ignition, neutral safety swicth and then activates the solenoid in the starter can degrade over time. Instead of replacing that wiring I ran a new wire directly to the logic circuit of the starter and added a new solenoid on that new wire. The old logic circuit now activates the new solenoid(which requires less current) and the new circuit activates the starter. I haven't had a single no start in over two years. I posted some pics in the 80 series forum. The solenoid I wired in was way overkill - a bosch relay would have worked just as well.
