I jacked up the wheels, released the dump level and turned the wheels by hands, the wheels seem sluggish with metal to metal noise coming from the axle drive. Is there fluid in the axle drives? I don't find any way to check for fluid, they seem to be sealed units. Scag manual doesn't mention anything about maintaining them. Should I be concerned? All these question started from my Scag SSZ 48 not going up hill well when the blades are engaged.