Aldot, what size chain is it???
You may be able to get a sprocket from somewhere else and make it fit. Using the old sprocket as a boss to hold the new one if the old was was fixed (welded) to the shaft.
Perhaps change both sprockets, you do not need the exact same tooth count as long as the ratio is the same.
Bearing supply and farm supply places that sell parts for tractor implements usually have access to a wide range of industrial sprockets and chain. Or you could try a motorbike place.
Cheers, Bob.
