I'm getting to know my new (to me) motor, which I like very much, but there are a couple things about it that I can't figure out with the Suzuki manual. First, there's a plug on the lower unit next to one of the gear oil plugs that's labelled "Flush." What is this for? Second, I'm concerned about running this motor on the muffs. When I duct tape the upper water intake and start the motor on the muffs, there's no telltale stream. Is this normal? I just replaced the water pump and it streams fine in the river.