Have a pool with spill-over spa.
We had the spa jets motor replaced this year with a 1.25 hp motor. Not the normal spa return, that is powered by the main pump.
When we hooked it back up this year, it works for sure, we verified the wiring is sending the water in the proper direction.
But we cannot the water to flow to the jets in the spa...
There is a valve (for whatever reason) after the spa jets motor (on the way into the spa) that I opened up to verify the valve was indeed in the open position. It was, and here is where it gets interesting.
With the jets motor on I removed the valve cover and sure enough water started flowing into the spa with no problems, and also right out of the open cover lol...
I turned motor off, sealed it up and works for the rest of the day.
But..... the next day we find ourselves back at square one, no water flowing to spa. If I repeat the removal of the random valve it starts working again.
We also have this issue a little bit with the main filter motor & another booster pump powering waterfalls. They both eventually pump water after two minutes.