I have a slightly stiff valve 1. It may be due to some roughening of the metalwork. Anyway I currently use lots of cleaning valve oil and work it which seems to free it up although when I return for a fresh session I have to rework it a little. It does work fine however, just a little noisy and has been known to be slightly sticky/stiff. I would just like it to be springier and quieter like the other valves.