1980 90hp mercury "tower of power" help

[DDrew]

I have a 1980 90hp mercury tower of power the slator wires have corroded the engine has 1 coil and a destructor cap when I try to start it the coil anit getting fire but if I tick the key over it will fire that 1 time if I keep ticking the key over sometimes it will putt and start up and after it's warm it will start back up if I turn it off if I stop the boat and fish for a while it's won't start again I'm thinking it's the switch box I need help on what to buy

[Ski]

Whats your serial number?