They should have said turn the wheel lock to lock slowly with the engine NOT running . That will purge the air from the system. That being said I don't remember having much trouble with older fords and air in the steering. Also theres gonna be a few air bubbles in just about any power steering system from cavitation. If it's groaning I would bet on a weak pump. I would use a turkey baster and empty the resevoir then top it off with Lucas power steering additive.