Buying a new carrier is easier.
There are a couple on eBay for around $100.
http://www.ebay.com/itm/YAMAHA-BANSHEE-YFZ350-AXLE-BEARING-CARRIER-40mm-w-BRAKE-STAY-/261220969393?pt=Motors_ATV_Parts_Accessories&hash=item3cd1fbabb1&vxp=mtr
http://www.ebay.com/itm/NEW-YAMAHA-BANSHEE-YFZ350-DRAG-AXLE-BEARING-CARRIER-40mm-/121262363284?pt=Motors_ATV_Parts_Accessories&hash=item1c3bccd294&vxp=mtr