Chris;
The operator is working on what I believe to be the Rudder Control Unit. The control rod that the BEA notes is bent rearwards, would be located at the top of the unit, not visible in the photo. I'm not sure what the round structure is - could be channeling or it could be structural - it's difficult to say where it is - underneath the RCU, or behind it nearer the airframe structure. There seems to be some robustness about it, especially on the bottom attachment - what we can see of it, anyway. I thought it may be APU pneumatic supply because of the shrouding but the source I have shows that plumbing to be on the starboard side. Still, manufacturing changes could involve routing changes, etc. The upside-down "Y" structure I believe is part of the rudder control cabling channeling, to do with the rudder mechanical control which is aft of the RCU. The sources I have aren't that definitive at times.