I have a Model 65 heater which I intend to install in my 51 B3B. I'm trying to figure out how the simple-looking defroster valve works. It seems to me the valve should open up when the defroster cable is pulled out and it should close when the cable is pushed in. From my perspective it looks like it would work opposite to that. Should the cable be threaded into the top of the hole in photo 2 or come up through the bottom? Should there be a spring somewhere to help close the valve or does the cable alone open and close it? I'm scratching my head on this one.