I discovered that the dosing head I'm using for my ATO wasn't keeping up. I tried to run it manually and at first it would turn slightly and then stall, but the motor was still running. I wiggled the tubes just to see if something was amiss there and it seemed a bit of plastic fell from the output side of the dosing head. After that, when I hit the manual button the motor ran but no attempt for the head to actually turn. So, I guess I need some replacement parts. The question is, do I need this: https://www.aquariumcomputer.com/usa/product/dosing-pump-head-for-ghl-doser-2-1/ or this: https://www.aquariumcomputer.com/usa/product/doser-2-1-pumps-maintenance-set/ Or all together something different?