With mur, the "gears" work, i.e. adjust the setting wheel in the lower part of the handlebar scale 1-8 clockwise or anti-clockwise: 1 highest, 8 lowest resistance when hitchhiking.

See if you still have an active warranty and possibly open a Galaxus repair case. I would not recommend touching inside as they are already adjusted gears and you risk creating more damage than solving the problem

You cannot switch any gears on the Homtrainer, but you should be able to adjust a brake to increase the resistance, i.e. to hitch more firmly. If the adjustment does not work, you will have to return the device for repair. Good luck