Darth Wagner said:
In the movie it's not specified how many tunnels Luke uses to get from the carbon chamber to that round window chamber. Theoretically there may be more different tunnels Luke uses - that would be an "exuse" for the wrong position of a round window chamber regarding extended arm access tunnel which Luke entered and exited in the movie.

Not quite sure I'm getting what you mean here Darth Wagner. Surely there is only one possible route of access to the suspended 'Vent Pod' as far as any kind of 'access tunnel' is concerned, and that is the single long 'extending support arm' isn't it?