EK43 Dial moving when switched on

Hey guys! I work with an EK43 in a cafe and I’ve been having this issue where the dial will turn (towards a coarser grind) whenever I switch it on, and more so when I am grinding doses.

I have already tried tightening the screws on the knob with an allen key, as well as the two screws on either side of the dial. It still moves and we have to constantly hold on to the knob as we grind to ensure that it stays put.

Has anyone else come across this issue or has a fix?

Thank you!!