Has this watch had the serial on the inside of this case-back not too subtly altered? That 4 is never original, is it?

https://www.chrono24.com/en/omega/v...4--id3637351.htm?urlSubpath=/user/notepad.htm

 

Looks original to me. The last digit of the case number is quite often slightly different from the others on these old speedmasters.

 

The 4 looks a bit funky, but the perlage around it looks perfect. i doubt someone could buff off a number and not alter the perlage. I think it is original.

 

Yes it's original, it's not the first time I see a similar number.

 

Well I never! Fair enough. Looked like a home made jack job to me, as if someone had gouged away with a compass point or something. Still got a lot to learn, clearly!

 

I seem to have given myself an earworm...

 

I suspect that the casebacks were made without the last digit, and the final year mark put on at assembly.

Just a theory, but it would account for the often seen final digit being wonky, applied with different pressure, and by what looks like a different person/time.