I was given this Matrix 12 book by Bert who wrote it for Oberheim. I ran into him at NAMM in Chicago back in the 80's and told him about the volume/Sustain situation. This was not in the original owners manual for the Xpander but it works on the 6R just fine.
Now for the bad news: As I recall, you have to take a day and set it for each patch that you want to use………
Sorry for the inverted scans but haven't been to bed yet…….
Charlie