That's the trouble with one power you need big muscles to work on a carpet when Henry is set on devouring it. It would have been nice if the one power option was advised before purchase
You can get a handle for the vac tube with a sort of hatch to allow bypass air and reduce suction at the head. I don't know if the standard Henry has this but if you measure the tube diameter you can get vac tools very cheap on fleabayg.
I don't know if the plastic ring on this one is a suction reducer.
£4.99
But this pic is from a Henry instruction book.