871251 on the label is the listed on the data base for a 1912 grade 992. What is the serial number on the movement? Judging from the enclosed literature it was a late model.
First, as Jim stated above, the 871251 is not the serial number, but an internal code for the watch, deciphered giving the movement, case style, and dial style.
see this image
Please use magnification to examine the serial number of the movement,
I believe what you are reporting as a "3" is a "5" (stylized font)
The case you show is really late, as is the outer box.
it is interesting with the small applied label on the outside of the pull-apart box, and the inner warranty paper.
what 'is of some concern is the other label. Not so bad as it is not affixed to the box, but that it apparently does NOT have the movement or the case serial number indicated on the label... those numbers certainly assist with validation of the combination!
this one is a bit different than yours, but shows my point...
Thank you for sharing the watch with us, please confirm that movement serial number.
I really do 'think' this one is right' no matter what you may read into my message ....