My internet search found nothing on that pump. I would contact Sheafer's Town & Country Sales Department and see if he can get one from Japan.
What is wrong with the pump?
Ouch, that IS a problem! I suspect you have already done an exhaustive search for this pump. The pump appears to be hard to find. I again would suggest contacting Sheafer's Town & Country Sales Department . The owner, Len Scheaffer is very knowledgeable and can sometimes get rare parts directly from sources in Japan. In the end, if you can't find a new pump, I would take the pump apart and take the broken shaft to a good machinist and see if they can machine a new one.