Bosch HBC Combination Oven/Microwave - Selector Switch Repalcement

[RealPolitik]

Have a Bosch HBC 84E 653B combination oven/microwave with a broken function selector switch (basically, it will only work on the microwave setting and no other positions on the rotary selector work). I’ve bought a replacement switch, which fits behind the fascia panel and the knob, but am not clear about how to access it.

Can anyone tell me if the whole external casing needs to be taken off, after removing it from the unit, to remove the upper fascia and dials/knobs?

This is the oven:

 

[RealPolitik]

No, just the top panel (for which it needs to be removed from the cabinet).