How to remove on/off switch Braun K600

Hello,

I have a Braun K600 Food Professor. It has an on/off knob. Through the centre of this knob is a pulse button.

The rubber membrane the prevents dirt going into the gap around the button has come off the knob. I am sure it will pop back on if I could take the knob off however, I can’t see how to do it. I’ve tried pulling it off, but it seems to firmly on for it to be a friction fit.

the button has come off the knob. I am sure it will pop back on if I could take the knob off however, I can’t see how to do it. I’ve tried pulling it off, but it seems to firmly on for it to be a friction fit.

I’m wondering if anyone is actually familiar with this knob and could advise me