I search on this topic, but I never really found anyone with a solid plan on how to do this. Also everything the searches came back with seemed to be old. So I have an old garage door opener that the nylon screw gears disinegrated. I am thinking I could fit it with a pulley and use some rope instead of the chain that was there. I am not sure this unit has adjustable start/stop points. Also my pop door is NOT a guilletine style, it is hinged on the side with a spring loaded door closer on it. Any ideas on how I could do this. If anyone else has done it I would love to hear what you did and if possible maybe even some pics?