ask a mechanic about speedy sleeve, its a thin press/on sleeve you could slide over your output shaft to make that sealing surface round again, being slightly larger wont matter because it rides on the seal, i've done this on cranks with no problems, measure the diameter of the shaft exactly down to the thousandth(vernier calipers will work) and tell a shop or parts store what you need..they're about 30 bucks
~Mark~