I'd guess that even if this the same Sanyo Denki they just made the part as subcontractors to Stax and either won't have stock or won't deal with the end user. http://www.sanyodenki.co.jp/en/
Stax are still in business but note that they are not accepting emails from the public and instead direct you to international distributor list. http://www.stax.co.jp/
Interesting that I sent this email directly to the dealer in North America and the responses come back through Tom's hardware. I guess Stax and the dealer aren't doing repairs on Stax!
Thank you for your reply. I guess I will have to go to a local electronics repair shop and see if they can find a Sanyo Denki drive unit for my Stax.