ARC on a Panasonic P50GT60B

[Ultraviolet]

Hello

Maybe one of you knowledgeable home cinemas types can help with a technical problem GT60b.
I'm trying to get audio back out from the screen to my av receiver.
I was planning on using ARC on the hdmi ports.

It looks like ARC is only available on HDMI2. However, this port doesn't carry video.
So I need to use HDMI1 for video (ie from the av receiver to the screen) and hdmi2 to get the audio back from the screen to the amp.

HDMI1 goes from monitor 1 on the amp (a marantz sr7007); hdmi2 maps back to monitor2 / arc on the amp.

This doesn't seem to work, even with hdmi control set to hdmi2 on the amp. Also, if I set hdmi control to hdmi 2, I also lose the function to switch off / adjust the volume on the amp and TV from the same remote (the TV passes this control signal back to the amp via hdmi 1)

Any ideas? Unfortunately I can't use an optical connection from the screen as all cables are buried in the walls!

Cheers,

Uv