The old bird feeder gave up the ghost last week and I replaced it with another half-broken feeder that the squirrels had worried at a couple of years ago. Here are a couple of pictures of the latest broken feeder. Note that the (heavy) plastic insides are supposed to be 3 levels high. One section is completly demolished, letting the other sections cave down inside of it.
It looks really good and the top locks down so the squirrels shouldn't be able to get inside. The birds seem to be happy with it although they were a bit hesitant because they have to really lean inside the cage to get to the feed ports, but they are learning to deal with the change.
Should be interesting to see how long this one lasts!