Rear wiper arm 2000 Silhouettte

I opened up the rear wiper assembly and it looks as though the large gear which drives the wiper has some worn out teeth in the position that is furthest from the park position. Anyone know if this gear can be replaced or do you need to buy the whole assembly. Seems to me this is a pretty weak link in the assembly. Vehicle only has 55,000 km on it so far. Between this part, a new drivers side window switch and rear gate interior grab handle this thing is getting expensive. Whats next, tranny and manifold gaskets? (I hope not!!) Anyone know of a good place to get parts in Ontario, Canada other than a dealer?

Thanks,

Mark