1985 Searay 140 Mercruiser i/o, starter will not disengage after motor has started. I've replaced both the solinoid and starter, (with newer gear reduction model)and a new battery with no change. Problem started as occasional overrunning and is now persistant. When starter is running, I can turn off the ignition switch and everything keeps running. I meter tested the switch and it appears fine. Now I have a short when I just turn the key on. I've only replaced parts and wired as original parts (not crossed).