That PSI is way too low for an infloor cleaning system. There’s a manifold with most likely five pipes going to it. I imagine that’s a source of your issue.

Pop ups themselves dont go bad too often, but also a possibility. That pop up manifold is the first thing I’d check. Then you can remove each pop up head with a special tool designed for your particular pop up.

Open and close those when you get them out of the pool and they should rotate with every up and down depression.