How smooth is your experience when the rig is moving? On my H2 I feel a constant rumbling when the rig is in motion. It seems to be coming from the right hand SFU gearbox. Feels like the bearings in the ball screw have flat spots or some are missing. Still usable, just annoying and unsure about lifespan of the unit. Also have not found anything in their literature about lubrication of the SFU gearbox. Anyone lubricating it? I have a request in with DOF about this, just looking for others experiences as well.