The dial, on our standard Dynamic, when turned to a new setting, "floorwell", "face", etc, has a fairly positive feel to it, clicking into the new selection and stays where it's put. Except for the last position, "windscreen". If I hold it in place and give slightly more, gentle, pressure it clicks home - at least half the time - otherwise it returns to about halfway between screen only and the previous selection. No problem in that air is directed to the screen, but as the rain is warmer this time of year and the demister is rarely needed, I'm uncertain if the screen is getting the full airflow it should as a result.
Anyone else have a recalcitrant knob or is it an <another> item for warranty when we go for the first service?

Have no probs with mine whatever setting/direction i put it to.

Take it up with the dealer.

I supposed there's a small chance that the control knob is not fitted correctly. You can pull it off, and underneath the rod it pushes onto has a 'star' like end, so it can be fitted on in another position slightly further round. To remove it, first pull off the smaller control that selects fresh or recirculated air. Then you can prise the whole '8' shaped plastic trim piece and the direction knob together and refit slightly further round. Worth a try...? (Has the bulb been replaced behind there? Maybe the knob wasn't put back in the right place)
Pete

Good Idea, I'll yoink it off later when the car comes home and try refitting. Nothing's been replaced, it's a new car - well, pre-reg'd, but with only half a dozen miles on it when we bought it the end of March.