Your understanding that the button should break the
connection of the two bars to stop the motor is correct.
The two wires must be joined together in some way
as the motor keeps running.
If the 90 degree brass bar is what’s missing it
shouldn’t take much to make one. You could make
a insulator too if its gone.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.