Received the package. The original box was just wrapped with a tinny black plastic, so it arrived in worse condition than the pictures, due to damage in the trip.
You told by PM that the cartridge was included, but you send me a wrong cartridge not valid for MAX.
I made the composite video mod to be able to test the computer, following this info:
http://www.6502.org/users/sjgray/projects/maxvid/index.html
In this web mention that Music Maker / Music Composer cartridges work with MAX computer, I have one from C64, so I plugged it and I only can see garbage in the screen, but presing a key I can hear the music playing, in the pictures of the web I can see a C64 MUSIC MACHINE working, so I think there is some problem with the MAX.
Also tested with a Versacart, following this:
https://retrofixer.it/en/max-machine-composite-mod/
Burning a ROM with MAX games, and I can see the start screen of the games, but then the graphics are corrupted. I don't know if this is normal.
If anyone with a working MAX could confirm this it will be very helpful.