This is a little bit worrying. I did see that someone came up with a permanently watering head that wraps around the UTM. This solves one of the issues of needing to change heads just to water. I kind of like that solution as it is elegant - but it needs to work.
I totally enjoyed the build experience. It was fun. However, I want (Need) something that works every time. I am going to continue with FB for now but if required I may redesign they UTM head and use an optical encoder for the detection - but if Magnets work - that would a whole heap less work.
FB - It appear that there are issues of reliability that need to be address.
@captainsemtex - Have you had issues with Z-Stalls? I lubed my Z axis and not it cannot hold itself up without always being power which appear to cause overheating and motor stalls.