Send an email to Gary at the voice of music audio enthusiasts, I would be really surprised if he can't help you out.
http://www.thevoiceofmusic.com
If it's an idler drive may want to send the idler in for a rebuild at the same time. I use wheel bearing grease with a few drops of oil on the centre bearing, it seems to reduce rumble to a lower level than using oil or grease alone. Also, a very good cleaning of all old grease and oil with isopropyl alcohol, and new rubber motor mounts.