My plumber stood me up, so I'm trying to figure this out on my own. It appears that the refill tube has broken off from the overflow tube. If I hold it in place, the toilet flushes okay. But when I release it, the pressure causes it to pop off and squirt water everywhere.

So my question is this: Is this broken piece part of the refill tube or the overflow tube? If it's part of the overflow tube, would I need to replace this entire unit and take the tank off to install it? If yes, I don't want to attempt this myself. If it's just a matter of replacing the refill tube, I think I could handle that. Hope the photo helps. Thanks for any advice.