^ in terms of the lock, there was a style of push lock that was used by a couple of design houses, including Chanel, during the late 1970's to early 1980's. I am a real sucker for preserving original parts. But, with those locks, I am willing to make an exception. The reason is that often, those locks seem to fail quite early in the life of the bag, and they appear to have been discontinued in the 1980's. I have one of the rarest styles of Chanel bag I have found, over in the USA for refinishing and a new lock right now. The choice was easy, because the original lock has no hall mark, so I don't feel I am losing anything.
The seal positioning depends on the country to some degree. Chanel Japan will reposition an original seal that they remove from a bag or wallet. But the USA does not.
On the flip side, Chanel USA will do leather treatment, but Chanel Japan will not. I haven't heard what Chanel Paris does - if anyone has experience with Chanel Paris, it would be interesting to know.