Hello, Derek,
The Green-trace and White-trace wires for the 'faulty' switch don't arrive direct from the Cpu board connectors, each will be wired to many other switches. It's the particular pairing of those Column and Row wires which are programmed as Left Boat Exit. Try following the two colours through the playfield wiring - the Switch matrix grid shown on the display in test mode (or even the manual) can identify which other switches are on the relevant Column and Row. The chances are a wire has broken off a switch further up the playfield. Though the boat assembly has a connector, too, AIR
Looking at the switch chart for Fish Tales, L/Boat Exit is No. 32, which denotes Column 3 and Row 2. So one of those trace colours will appear at any switch with first number 3 or second number 2, which are Right Boat Entry and Exit, Spinner, Reel Entry, Reel Optics (2 switches), Catapult, Top Right Loop and Centre Jet Bumper