I have a deep well jet pump(Berkley 1.5 hp). It is an upright sitting on top of a 2" sch40 pvc pipe. It is a multistage with the pressure regulator. The 1 1/4" inside pipe goes down 40' with a water level at about 20'. It runs my irrigation system for the house.

Now my problem:
It loses its prime regularly. I had to replace the pump recently(15 years on the other one). While changing the pump, I changed the jet/check valve on the bottom of the 1 1/4 " line. I thought this would take care of it. No luck. I have rigged a hose hook up where the gauge on the pressure regulator should be and prime it with domestic water every time I need to water.

I did not change the gasket between the pump and baseplate or the seal gasket between the baseplate and the 2" pvc. Mainly due to me not realizing they did not come with the pump but needed to be purchased seperately.Duh! Both gaskets looked good. Could either one of them be causing the prime to be lost? If not maybe a defective jet/check valve in the hole? When I removed the original jet from the hole. I had to rig a come along to get it out. The one in there now can be pulled up by hand. Could the way I installed the new jet have damaged it?

I have tried to give any pertinent info. Any assistance is greatly appreciated.