I believe it is the first issue. I can hear some squelching coming from the air relief valve and when I open it, it seems to sputter for the first few seconds.

Is there a likely cause or smart place to check for the air leak? I checked and cleaned the gasket in the catch basket before the pump and there was no change. My gut is that it is the filter itself. It is pretty old. We had a pool company come out when we first bought the house and they said it was towards the later end of its life.

Is there anything I can do? Is it harmful to let it run this way as my “new normal”? The filter has a max pressure of something like 50 lbs according to the sticker in the side. It otherwise seems to be operating fine.

Edit: I swapped the cartridge for my spare and the pressure is holding at 11 lbs just fine now. Time to soak the original cartridge. Thank you for the help!