[Marc-André Haldimann]

Christian, Steve,

Thanks for your inputs! Christian, a (F) 122 machine would be just fine, explaining the odd position and high number of this machine...

Steve,

I just tried to read it myself; it's a tough exercise as the pic is reversed. After trying, I would concur that the first two digits are 77 and the last three are 355. This overlaps well with the reading provided on a comment posted by the original poster over at Flickr whiere he claims to read with a magnification glass, and not without doubts, the W.Nr. 770355.

Cheers
Marc