American Standard push-pull

I replaced the guts of an american standard push-pull faucet: drawing number N 1030-1. After replacing the seat, stem and springs (entire kit) on both hot and cold I now have a problem with lack of water pressure. There isn't enough water pressure to activate the shower. Both the hot and cold works but only a trickle of water flows from the faucet. It's like the stems are not opening up to allow the water to flow.

https://terrylove.com/forums/showthread.php?53413-American-Standard-Push-Pull-Shower-Valve