i can't see that it is anything to do with the truck-mount, like others i have cleaned thousands of meters of carpets with one and never heard of this sort of problem, you may have left marks where the ends of the wand have been and she sees that as a gouges in the pile, i never used to 'dress' the pile until someone rang me to say that i had left unsightly streaks on her carpet, turned out that because i didn't brush the pile one way when finished it dried with the pile laying as i left it, i had to go back, dampen the carpet and set the pile, it was ok then. i set the pile now!
colin