Re: xy fairmont tailgate
Try to find the source of the binding. Remove the covering panel inside the tailgate, and disconnect the regulator arms. The glass should then be able to be pushed down and the tailgate opened.
If the glass slides freely, the binding will be in the regulator assembly or the motor. I recommend removing the glass from the tailgate, then try to operate the switch to see if the regulator assembly moves freely. If it does, check the rollers for wear and correct lubrication.
If it still binds, remove the motor, check operation. If the motor turns in both directions ok, the regulator requires inspection, alignment and/or lubrication. Otherwise, either motor, wiring or switch is at fault. You can trace this by hooking the motor up directly to 12V to see how it goes.