I have a 1990 Merc 350 Magnum -- I've had a problem with the engine starting, I will turn the key and I hear a click in the engine compartment. Everytime I turn the key one click. Eventually the motor does engage and will usually run good for most of the day but somtimes it will do the same thing when I try to crank her up on the water. I have repaced the ignition swith and the starter $$, but I continue to have this problem. Any suggestions on what I need to check out? Thanks in advance!