you didnt mention what voltage you are starting your engines on? all the above is good practice, but without the proper voltage, it wont mean anything. chances are there is nothing wrong with your starter ( unless it is powered by 16 volts plus). i have a sullivan hi torque starter that is 20 plus years old. i start my 80-90 with 2 7 cell panasonic sub c car packs. if the charge goes down, no matter how much i clear the engine, it aint turning over. charge em up and good to go.