I am adding the widget to my file, and I notice that your rs232 commands don't match what I currently have in my file.   I got mine from the marantz excel document on their website.

for instance, my Game input code looks like this:
@SRC:O

yours is:
SIGAME

my code works, I haven't tested yours.   

are you working off a different protocol sheet?  here is the one I am using:

[Link: us.marantz.com]