Hi, new owner too, so i can't really help for the Automix import. But I got pretty good at tearing it apart since i have two faulty channels!
So yes, the SENS knobs are removed by pulling them up. But be careful : they actually consist of a white plastic sleewe (with pointer on top) put on a rubbery black body. If you lift them, you may end up only getting the white sleeve, and accidentally press it between your fingers and break it.
I had the less issues with this sleeve slipping by turning the pot to point at 9 o'clock, and place my thumb and index at 6 and 12. This way you press on top and bottom of the actual "D" shape of the axis, and it slides better without sleeve slipping.
I had one marker broken on my unit, it glued perfectly back in place (there's not much strain on it anyway).
ANd finally, i didn't find any matching replacement. If you do, let me know! But you can easily find 16 equivalent narrow D-shaft knobs online i guess...