Yep, I have the same issue, brand new keylab essential 61, but I think that (at least in my case) it's a mechanical problem. I mean, when I turn/adjust the issued knobs, I can kinda feel a strange tactile thing, I mean, they're more "weak" when adjusting them, compared to the working ones, and also I can feel like there's some sand (idk how to describe this), like they're "clicking", but very softly (sorry for my super-crappy B2 English that's actually dying in convulsions ahahhahaha). And, well, I guess it's not such a dramatic thing (well, when I'm adjusting something like filter cutoff - it is lmao), but come on Arturia, I've paid this thing 240 euros, are you kidding me?