thanks Alpha1!

I have look at the power supply, but but it's only a yellow switch there. no additional switches. argghh, that is no good.

here a picture from the (still dusty) power supply:

Mhhh, what to do. Ahh! I take a look in the xevious cab, and i have found two switches on the power supply in there. the blue one was connected on the xevious power supply, the brown one was in addition. puh, what a luck, but can i take the brown switch from the xevious for the millipede? i am grateful for help!
Here the switches i take off from the xevious:

a closer view on the power supply shows me that on the plug the earth's cable is cut off.

that was not normally, or is it?
here in detail:
