Ok, so my pump has been losing prime for a while, but it started to get really bad a couple months ago. Since then I have fixed a few obvious pump area leaks: gasket on junk catcher basket (+lubed), spider gasket on multi-port, o-rings on the two three way jandy valves, the run of 2" PVC pipe connecting the pump outflow to the multiport (there was a small drip).
After I was done the new PVC run, I noticed something I should have observed earlier. Take a look at the image, the jandy on the far right connects to the skimmers (far side) and bottom of pool (close side). The jandy to the left of that brings in the return from a slightly elevated spa.
When the flow to the pump is only coming from the spa and then I shut off the pump no air gets into the system. When the pump is on and I switch the flow back to the pool returns I get a reasonable amount of air. If I turn the jandy on the far right to bottom of the pool only I get more air, when I turn it to the skimmer returns I get air, but a bit less.
So at this point, did I miss anything obvious? It seems to me I have a suction side leak somewhere on both of those returns. Appreciate any insight.