[JERSEYDEVIL]

was the original switch a 3 wire also?
one possibility is w/ these older carters they were wired for lack of a better term that i use to describe it is "reverse ground".
basically with these the switches and accessories are wired where grounds complete the circuit at the throw or use of every switch. for example the headlights are wired hot and the ground wire runs to the switch. the headlight switch when turned on completes a ground instead of contacting a hot wire in line to the light. kind of "reverse" of the way most of us wire something up. so when diagnosing you almost need to think a lil backwards, kind of like turning a wrench on a nut that is behind something facing you.
one more example of how weird these can be. ive owned a few carters, 1 of them needed a tail lite so i made a bracket and used an oval LED tail light. i wired the tail & brake wires to the harness and the ground wire of the light i grounded to the chassis instead of the harness. everything was fine but when i stepped on the brake it killed the motor. i thought about it for a second and moved the ground wire off the chassis and spliced it to the harnesses ground for the tail light, issue went away. point being that if the switch isnt identical replacement than maybe the ground on that switch is in the wrong spot and killing the motor.