Ok so one of our hydrocuts gets stuck in reverse a little when you let go of the handles. So if you shut off the blades and step away to pick up some trash,open a gate, move something in the yard. It will start backing up. Sometimes more than others, but if you slap the back of the thumb controls forward a little it will stop backing up and sit still. What do you all think could be causing it? We tried adjusting the metal rods a little but that didn't help.