Shurflow 4900 series pump problems

Through process of elimination I found the valve assembly on my water pump to be the problem. I had replaced that a few months ago and thought I was good but it was a short fix. I took the pump out and hooked a garden hose to the outlet side of the pump and had a steady drip from the inlet side. I removed the valve assembly (there is no check valve in this model pump) and inspected it, cleaned it and put it back together, same problem. Hit the local Ace Hardware and got a 1/2 inch check valve and put in the line on the suction side of the pump and after several hours I see no leaks and everything seems to work. Keeping my fingers crossed.
Thanks to all who added helpful suggestions! Dick