Hi Jon, I just checked my pump on two planes. 2-position is set to 0% for off and 55% on. I guess it was lower then I thought. Some people are concerned that they fail. I can't prove this, but i think mine have lasted since I don't run them really high all the time and have them set to one standard flow rate. You're just providing the Kolm a little more efficient flow. I've only been using them for about 3 years now, so I might replace my oldest one next year as a precaution. Some people probably have a lot more experience then me...
As for check valve, I got mine at Dream Works. Their new web site is a little challenging but here's the links to two that I've used... Sullivan is OK for the return, or the secraft is really nice. I'm using that one for the ghost but ran the sullivan check valve on my test stand for the Kolm.
https://www.dreamworksrc.com/check-a...hon-valve.html
https://www.dreamworksrc.com/secraft...-valve-v2.html