Dualit repair?

I have a Dualit 4 speed 300W hand mixer Chrome, Model HMR1. I want to check the 'On' trigger, which seems to be overheating a bit on prolonged use (is this normal?)
I have popped the plate where the mixer wands are inserted, but cannot see how to further dissemble.
I am experienced at electrical servicing, and have a well-equipped workshop that includes electrical test gear.
Thanks, George