How do I purge the transmission on my new tractor before first use?

Start the engine and move the throttle to the slow position, then slowly move the motion control lever to full forward and hold for five seconds (approximately 40 feet), then move to full reverse and hold for five seconds (approximately 20 feet). Repeat this procedure three times to fully purge the transmission of trapped air. This step is required before operating the tractor for the first time and also after any transmission removal or replacement. (Page 14-15)