I noticed in my recent newsletter from SmartHomeUSA.com that the drapery motor we haver been using to open our pop door has been revised for chickens. They have changed the pully so it does not requirs a counter weight. I wish I had known this was coming I would have waited. Here is the link:
http://www.smarthomeusa.com/ShopByManufacturer/Add-a-Motor/Item/D20/?aw=174/
http://www.smarthomeusa.com/ShopByManufacturer/Add-a-Motor/Item/D20/?aw=174/