How to identity original Le Corbusier Grand Comfort  

Quick Google search came up with this website . . .
from the article:
Rule 3: Know where to find the serial number. On Le Corbusier?s LC2 and LC3 chairs, feel under the upper-most chrome bar on the left arm of the chair. Authentic chairs have a serial number etched into the chrome ? you can feel the bumps with your fingers. On some vintage pieces, the placement of the serial number may vary ? sometimes it?s behind the backrest or on the right arm bar ? but most years it was on the left side.
From the Cassina website: ?According to the designer?s heirs ?all pieces of furniture which do not bear the logotype Cassina, the signature of Le Corbusier and the production number are counterfeits?. All authentic Le Corbusier furniture is indelibly marked with the indicia shown below.?
http://jetsetrnv8r.wordpress.com/2008/08/28/vintage-furniture-corbusiers...

Thanks!
I don't have the piece in my possession yet, and I didn't inspected the frame closely upon my visit with the previous owner to know if there is a stamped number on it. I was puzzled however by the black rubber straps and was hoping somebody could help me with that if that might proof to be significant. I also have to have to point out that the frame is not chrome but made of steel which is painted black and has been worn off due to it's many years of use.