broken sliding door guide on shed

Hi all,
I have an old metal shed (no idea what make) with sliding doors. The plastic guide thing for the door just snapped. I've had a google and have struggled to find anything like it.

Anyone know where might be worth trying? I'm usually pretty good at finding anything on the net but this has me stumped...

Cheers

anything you can do with greenhouse door tracks?

would sliding mirror runners do the job?
Grendel