REPLACING A FAILED NEFF OVEN ROTARY CONTROL?

Our NEFF combined fan and microwave oven Model: B6774N0GB/04.

The rotary time and timer control has come loose. It extends further than the other depressable rotary control. Also when turning anti-clockwise to adjust (reduce) the time it will not move past the 2 o'clock position. I need help in diagnosing the failed part(s) so that I can obtain and fit the new part(s). The parts diagram is here:
http://www.neff-eshop.com/eshop(bD1lbiZjPTAwOQ==)/neff/gb/prodp.htm?prod=B6774N0GB%2f04&ESHOPTYPE=S

Can anyone help me please?

Thank you