I suffer from the first of the problems you listed, sometimes when I turn the knob only a couple of notches the setting goes the wrong way

Same here.

I sometimes see the second issue, with the volume/menu taking a while to catch up with my movements.

I see that also sometimes, and I've got a Mk2a so slipping shouldn't be the cause. Actually I have never seen one of the two issues on my Mk2, but I havn't used my Mk2 much since I have the Mk2a.
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_______ Thomas