So I just added a V-green 165 VS pump to my system after my pump motor locked up on me. I had to replumb the pump housing and motor because the new motor wouldn't fit with the old configuration. After the replumb and changing out the shaft seal and all o rings, I can get the pump to prime when the multi port valve is set to filter. Oddly, it primes and works perfectly if the valve is set to recirculate. FYI, I also changed the spider gasket in the multi port valve. I'm lost. Why would everything work properly when set to recirculate but not when filtering? Help!