Tractors

Pg 6 of the Quick Reference Guide says to purge the transmission before operating the tractor for the first time.  I just received this unit today, so this is the first time operation.  The procedure begins with:  have the engine off, set the parking brake, and disengage the free-wheel control.  Then start the engine and release the parking brake.  The problem is, you have to have the parking brake set to start the engine, but as soon as you set the brake the free-wheel reengages.  Help!