Re: gearbox
almost right, don't know why they are red. bottom is drain and fill, you fill from bottom to get the air out. top is vent and full level. no you do not have to drain to do the impeller, but it is advisable to change the fluid every fall, before the first freeze, in case of water intrusion, water in the lower will freeze and crack the lower unit. always replace the seals when you remove screws.
