logjames Could it be they clipped a ring or the one is slightly compressed? In any case, I swapped them last night and I am not currently seeing this issue. In one of his videos, Mauro mentions not to mix up these springs, which I had thought odd since they have the same part number,
It might be that the springs receive a different amount of compression depending on where they are placed. With the top valve, water pressure helps hold it closed and it’s only slightly compressed more to open it. With the preinfusion spring, it’s constantly under more tension to provide an 11 to 13 bar resistance against water pressure trying to open the valve.
So yes, over time (certainly 2.5 years)…,it’s likely to be a little shorter (more compressed) and it would be good not to mix them up.