I just picked up a used John Deere GS45, 48" walk-behind mower. I thought all of them with the Spicer transmission had 5 foward speeds but I only have 3 speeds with this one. The shift lever does not move beyond 3 toward the indicator sticker for the transmission. Also there is a big jump in speeds from 2nd to 3rd - 2nd is too slow to mow in and 3rd is too fast and bogs down the motor some if you are cutting much of any grass. Anyone have any ideas? I didn't get a manual but the online versions show all models as 5 speeds.