Running a 8200 flex head with sch drive. Book says to slow header drive all the way down which is around 380 rpm before switching coupler. Seems like sickle speed is too slow. Can only run 3.8 mph and get a decent cut. Header book says header drive shaft speed is 608rpm. Do I need to speed it up and them switch hose to the reel lift. Also running crary air reel and couldn't find any input speed for that. Thanks