Recently the PB came to do the follow up cleaning after opening. There were lots of dirts, pine needles, leaves on the bottom of pool. Now I can see air bubbles under pump lid. It is like a stream of tiny air bubbles circulating in the basket. Pump is priming fine. I can also see bubbles coming out from the return jet, but they are mostly individuals instead of a stream of lots of bubbles. I checked the lid seal, drain valve. All look good. The pump is 5 years old. Not new, but not very old either. I suspect the bubbles might be related with the cleaning work PB did last week since I didn't see the bubbles in the basket 2 weeks ago When pool was opened. But don't know the next step
Any suggestion where to start now? Thanks.