Here’s an update. After having the original pump installed water is flowing again. It took about 10-15min for the pump to gain full suction though. Initially, water started to trickle through the pump’s inlet, then it gradually increased its stream as I let the air out though the relief valve. Not sure whether it is normal or not to take that long, but I can’t seem to detect any visible leaks in piping after having run overnight. Now I need to test the other pump this evening. My hunch is that it’s going to work just fine and that I should have just let it run while installed to gain full suction, but I’m a noob after all…