Thank you @Rancho Cost-a-Lotta and @BillyMac96, I ran a temp hard line from the pool to the pump, and what do you know, the pump primed again! I've got water moving again - thank you again for your help! Although the pump does prime, it does not prime perfectly as there is still some air in the basket (pump basket gets 3/4 full with water), and it slowly drops to 1/2 full with water after running for half a day. My hypothesis is that I think I have a weak seal at the drain plug, as I inadvertently bought a non-oem replacement. I have the official Hayward plug arriving today which I will replace. Although I have seen no water dripping from this plug, I guess it can still pull in some air from it.
My next challenge will be to determine where the failure is on the piping from the skimmer to the pump. My first hypothesis at this whole problem was a clogged skimmer line (as I get tons of debris in the pool), but I had two different techs blow the line with compressed air and CO2, and no blockage was found. I guess it may be in the PVC joints/fittings above ground where it attaches to the pump (as I already replaced and lubed the gasket there?
My skimmer basket has two holes, and we think one runs to the floor drain in the pool, but the tech could not blow air through through that line and out the floor drain - so maybe this one could be clogged and causing this whole issue? He also mentioned that this line from floor drain to skimmer basket is sometimes capped (don't know if that is true), which is why I did not pursue cleaning this route initially. Don't know if I should try to snake this myself, or camera it.
Temp solution:

My next challenge will be to determine where the failure is on the piping from the skimmer to the pump. My first hypothesis at this whole problem was a clogged skimmer line (as I get tons of debris in the pool), but I had two different techs blow the line with compressed air and CO2, and no blockage was found. I guess it may be in the PVC joints/fittings above ground where it attaches to the pump (as I already replaced and lubed the gasket there?
My skimmer basket has two holes, and we think one runs to the floor drain in the pool, but the tech could not blow air through through that line and out the floor drain - so maybe this one could be clogged and causing this whole issue? He also mentioned that this line from floor drain to skimmer basket is sometimes capped (don't know if that is true), which is why I did not pursue cleaning this route initially. Don't know if I should try to snake this myself, or camera it.
Temp solution:
