Thanks I remember reading similar but can’t find, as if he was deleted. “avoiding downward cuts which rely on gravity for force and don’t have much tension from one of the motors to overcome pull from the bit would apply.” Is only an explanation why every downward cut near bottom corners is a problem with current setup… we aren’t taking that as a nail in the coffin right? 
Any thoughts on what else we can try besides 12 foot header (which requires new chains and loses ability to use standard software? Otherwise we have dog leash for bottom tensioning to try