If they are henned up and not just call shy you might want to try to bust the flock like you do in the fall. Sometimes that tom will get a whole pile of hens and will be content to sit there and strut and basically ignore all those calls you are making. With that many hens already he isn't going to go to a call. But if you can break the flock up and get him seperated from the hens all of a sudden that bird becomes real callable (if that is even a word). Or better yet you might be able to set up and have the real hens call him back to you. Just another idea to think about.