We have just recieved our new Byrd Shelix planer head for our Bridgewood BW508 planer. But we don't have the owner's manual and can't figure out how to take the old head out. Most of it is pretty straightforward, but the drive gears on the left side are stumping us. I tried calling Wilke Machine, but get a busy signal. Byrd was no help, they sent me to Wilke. Does anyone have any advice?