Is it just the one that's missing? If it is, I'd just plug the hole with something and let the hummers drink out of the other three ports. We can get bee guards at places like WalMart and some of the pet supply shops, too, so you might want to check locally before driving any distance to get them.
"We are--each of us--dying; it's how we live in the meantime that makes the difference."
"It's not what you gather, but what you scatter that tells what kind of life you have lived!"
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."