Brother MFC-L3750CDW - rear paper rollers grinding

My relatively new Brother MFC-L3750CDW has developed a fault where the upper rear paper feed rollers are grinding noisily. It looks as if some teeth on the plastic gears at the side have broken off or worn down (see photo). Does anyone know if this is a relatively easy fix and how to do it? I’ve tried taking the side panels off, but the gears I need to access look like a nightmare to get to. Thanks!