Nevermind. I found the service manual with all of the part numbers included. If anyone else has the same problem, you can find the part here:

http://www.partsimple.com/vu931600-yam-n-13.html

Sorry to dredge up this old thread, but does anybody know anywhere ELSE that I can find replacement knobs for this synth? It appears that the aforementioned website no longer has them listed.