Hoover Power Scrub Carpet Cleaner FH 50150 . Had burning smell and noisy. Took apart found motor housing that turns the brushes gears was rusted out and stuck. Installed motor unit that turns brushes. Cleaned out brushes and it spins freely. When I start unit the brushes barely turn. If i take my hand and cover that one hole that the waste storage container sits on the brushes turn so strong your hand can't stop the brushes from turning. Ss soon as I remove my hand from the hole the brushes slow down and barely turn. Am I missing something. Thanks