How decide if the pump is putting out enough pressure?

Gaskets? O ring failed and it plugged a hose? Cracked housing on a part you can't see without removing it? I'm guessing possibilities. If your brewer gasket was bad, I think you'd see water or steam.

Hi Micheal, did you manage to resolve your Portafilter issue? If not, which coffee machine do you have? I’m currently using a Breville Barista Express machine and haven’t encountered any issues. I did recently purchase a Joefrex pressure gauge just to check the pressure it’s producing which may be helpful in identifying your issue.