The way this starter works is the springs push the paws out and they catch in notches in the flywheel. When the motor starts centrifugal force pulls the paws in. If a spring is to strong the paw wont pull in and you’ll here it clicking on the notches of the flywheel as the motor runs. A friend and I tried to make some and we didn’t have the recommended guitar string. What we had was heaver and we could never get the tension right so the paws would pull in. From our experience I think these springs are hard to get just right.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.