Hi - I just installed and tested my 45MPHP10 fixed rate pump (10 gpd) with 1/4" black tubing and it is pumping at around 30% of the expected volume. I checked that the suction tube is not too far in the suction weight and the pump head tube appears to be correctly set. I also collapsed and expanded the roller assembly, with no change in output. For the test, I ran it 18 minutes, which should pump 16 oz of bleach (1280 oz/day capacity * 18/1440 time running = 16 oz) and only had about 4.8 oz of output.
I will follow up with Stenner tech support next week, but if anyone can offer some troubleshooting advice, it would be appreciated.