Q to owners of imported BMW from Japan

[shogun]

This probably goes mainly to our members in Australia and NZ. I have a Sony Audio in my 750iL and I am looking for a instructions manual/owners manual and/or wiring diagrams either in Japanese or any other language for this equipment. Not absolutely necessary that it is cpl. identical, if similar, it would also be o.k. BMW Japan does not have it anymore, also SONY Japan does not have it. Their headoffice is in walking distance from my home in Tokyo. Went there, but no success. It was installed around 1988 in BMW's of the 7 series in Japan as standard equipment by BMW.
Want to keep the original equipment inside, but need some wiring diagrams etc. in case it has to be repaired.
Pics:
http://www.arcor.de/palb/alben/49/622249/1024_3035653566343063.jpg
Above sits in the front panel as control unit. Below pic shows the second control unit in the armrest in the middle between rear seats. The rest is installed in the trunk, incl. 10 CD player.
http://www.arcor.de/palb/alben/49/622249/1024_3130366638623963.jpg
http://www.arcor.de/palb/alben/49/622249/1024_3133613232373737.jpg

SONY CDX 5B817
CD AUTO CHANGER SYSTEM
FM-TV 76-90 Mhz, 1-3 Channel
AM 522-1628
DC: 12 V negative ground
serial no. 11165

Thanks for reading and I hope to get some feed back.
I am also interested in some spare control panels or the main unit as shown above, does not matter if they are defective. Will try to repair them.