Thanks for all the suggestions.
There is no button on the outside of the body. I took the line off the bottom of the proportioner and tried to push a small allen wrench into it to see if this would move the valve. It didn't seem to work. I am thinking of bypassing the proportioner with the rear brakes. The kit I bought included a regulating valve to adjust the pressure to the rear brakes so I am thinking it won't hurt to bypass. Anybody know why this might not work?