SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

I agree, it sounds like there is some debris in the valves. It's possible the diaphragms are ruined. It's usually the valves on the end of the manifold that take the hit when dirt gets in the line.
Just pay close attention to where everything goes. There's nothing to it really. If you forget then just take apart another valve. Here's a link to answer all your questions about the PGA valve. Good luck!

http://www.rainbird.com/pdf/turf/man_PGA.pdf#search='rainbird%20pga%20valve'