Hi just ran into this same problem. I have the same receiver and a RM-VL1000 Sony universal. It should just work because they are both Sony but they don't. The receiver is 2005 and remote from 2003. I have looked everywhere for codes and nothing worked. As a last resort I tried Peel remote app on my phone, searched receivers under sony, and on the 9th or 10th one it connected. I then set in the receiver model number in the app. Then with the learn feature on the remote set the buttons to the matching ones from the app. It worked! So I don't have the exact code for the receiver I was able to hard code it into the remote, but I had to use the Peel remote app. Hope this helps others.

Sony AV System Remote Control RM-AAU001 is what I have found to be the remote for this receiver, so if anyone knows the code this remote is sending out it should be the correct code to the receiver. Does anyone know this? Thanks!