I have a Sebo x1. It will not pick up from the...

Question

The unit has had the filters checked, hose o.k.
The middle wheel seems to be at its highest level, and the brush roller is approximately half an inch from the carpet even in the cleaning mode.
After removing this wheel it seems to motorised, how does the machine adjust the wheel itself.
If the head is pressed down with my foot it seems to operate as normal.
Regards
K Hammond