Omega Seamaster O-Ring Help!

[onthepond]

I have searched Omega, Star Time Supply ... and cannot find a listing for my friend's Omega Seamaster Professional 300M in need of a case back O-Ring / gasket.

The case back lists it as 196.1502; however, the Omega website does not show this watch. The 396.1502 ('93) shown under Vintage watches is a mirror image of this piece (including bracelet), albeit, there is little detail as to size ...

The O-Ring groove / seat measures: OD 1.320 & ID 1.233 (approximately). I did not want to remove the present O-Ring a 2nd time, as it is damaged and old, making the measurement somewhat iffy. That was verified when changing the battery.

Any help would be appreciated!!