I have a 1984 470mercruiser. The motor was running and stalled When I restarted the engine the starter motor continued to engauge and turn over the engine. After I lifted the battery terminal to kill the power to the starter it stopped . Now with the slave solenoid and the key ignition switch completely disconnected the starter turns over the minute I touch the wire to the battery terminal. The starter was replaced this past spring and has only been used to start the engine 3 times to date. I am presuming I have a bad solenoind on the starter.

