Hose and focus guide melted

The rubber hose that connects to the laser head melted on my BeamBox as well as the focus guide. I can’t seem to find either part in the replacement parts available. Nor can I find a clear description of how the hose functions. I assume it’s for cooling. I’ve been jamming it back on but after a few runs it pops off again.
I have a picture here.
Any suggestions? Help?