It looks as though the broken jaw is a separate piece from the ratchet part. This might give you the option of making a replacement piece in, say oak or beech. I doubt it would be a lot weaker than the original, although these things are usually glass-filled plastic and stronger than they look. You'll probably just have to remember not to stress it as much. You might also put a flat plate on top of the broken piece (hardwood again, secured with countersunk machine screws through the plastic into nyloc nuts or similar (don't even think about using self-tappers or similar). I'd ditch the red plastic pads and improvise something else, for example leather.
But like everyone else, I'd first contact Bessey and find out about a replacement. These look Chinese made, and I seriously doubt they cost Bessey very much to buy in - profit from them probably covers better clamps that sell in smaller quantities and cost more to make. They ought to be accommodating, as I can't come close to breaking my equivalent Axminster/Rutlands* ones by squeezing by hand alone.
"No sir, you'll never see a broken down Rolls Royce on a tow truck." RR would like you to think they don't break, but actually their recovery vehicles are all covered wagons...
... contact Bessey and see.
E.
*Rutlands ones are green, Axminster's ones are red; both have own-brand stickers on them, both probably work just the same. Mine are red ones (and jolly good they are, too).
