The gear grinding seems to be an issue across other models as well. I just bought an HU800AWD today and had to take the first one back because the two gears weren't meshing at all and were actually slipping! The second one I got was not near as bad until I started mowing with it and I found that at low speeds, it seems to slip like the first one did. Thanks Timothy, I will try the washer trick and see if it helps.