Urinal valve question

At our community pool we have an stinky urinal. Someone shut off the water flow screw because it would just run continious.
I took off the top cover and pulled the diaphram. I'm assuming it needs a new Sloan diaphram? I'm not solid enough on how these direct pressure systems work though. I can rebuild a home toilet blindfolded.
Any educational links, answers, advice , is appreciated

You will find plenty of info here: http://www.sloanvalve.com/

I generally rebuild the entire valve. Sloan has a kit with all the new stuff in there. That said, you really should check the pressure and the volume at the fixture. Many of the old Sloan's need a lot of water to operate properly.