[Hudson River Steve]

Here is a good site that explains the operation of the entire shift system.
Replacing your Alpha One shift cable.

I had an older boat with an Alpha One drive that had the same problems. The shift cable out to the drive had worn through the outer casing where the exhaust exits the boat, when I put pressure on the shift cable it would kink slightly and cause excessive friction on the cable. This would cause the spring loaded shift plate to rotate, activate the kill switch and cause the boat to stall. I replaced the shift cable to the drive, adjusted the microswitch and it shifted like new.