As the title says, my 09 matrix XRS (225,000km) has a bearing hum, suspected to be coming from the transmission. The hum gets louder with vehicle speed, doesn't matter what gear I'm in or if I'm in neutral and coasting. Both wheel bearings have been diagnosed as not the cause of the him, and my CV shaft was also replaced, but the hum remains. My mechanic believes it's from the transmission. If it's a shaft bearing in this transmission, would it be worth trying to replace the bearing, or just swapping transmissions?