Could try HS Walsh, who carry replacement barrels, example here.
I’ve no idea if the size and tooth counts available will match your clock, fingers crossed!
Otherwise, repair by soldering on new brass and filing to shape. Skilled work needing practice so don’t jump straight in. As acquiring the tools and experience may be more trouble than it’s worth for a few odd jobs, could be one for a professional clock repairer. But it’s certainly do-able if you have time, enthusiasm and steady hands!
Dave