I have my Yamaha KX 88 connected to a Gem Real Piano Expander. There are some problems with controlling the Expander with my KX 88 (for example the Pitchbend wheel is not working well and the breath controller and aftertouch are not working).

I want to control the Gem module via System Exclusive messages. My question to you is:

Can you give me some concrete examples of Sysex string commands, that I can use for controlling the Gem Real Piano Expander with my Yamaha KX 88? I have tried many times myself, but it doesn't work. I am desperate.

I do know this: F0 (status byte), 35 (Gem Manufacture ID) ............. F7 (end of sysex)

I have already downloaded the miditables from the web
(Maybe, there are other solutions to this problem).

Also, how can I change the velocity of the KX 88? I guess this also works with Sysex. Can you give me the command?
Is there any other literature about the Yamaha KX 88?