Another option to solve rain water leakage would be to attach a fairly large lid to the top of the feeder so the lid sheds water. Two things I would consider to use would be a garbage can lid (plastic or metal) or an upside down round snow saucer. Just attach the lid with a few screws or maybe put a piece of wood on top of the lid and screw the lid to the wood. With the lid in place you would not have to tightly torque the top to the feeder.
