Letters and numbers scratched into the back of the back

[InsideTrader]

I own what I believe is a 1970 Datejust that I have had for about 8 years. The grown came off the stem the other day so I took the back of the watch off for the first time to do the repair. I had never seen the inside of a Rolex before. I was surprised they are battery powered. Lol jk :) Anyways, on the inside of the watch back were a series of letters and numbers scratched into the watch that were obviously not factory but seemed to mean something. H-74303-N11 Does this mean something or are these just some random numbers scratched into it by someone and their meaning is lost to history?

Thank you guys for any help.

[kieselguhr]

The last technician to work on the watch writes on there

[Stud Screw]

Ditto that. Good luck with the repair!

[InsideTrader]

I appreciate the info. Is there anyway for me to know what they mean or do all technicians use different codes?

[kieselguhr]

Originally Posted by InsideTrader

I appreciate the info. Is there anyway for me to know what they mean or do all technicians use different codes?

Maybe a resident TRF watchmaker can comment on this.

[robmack]

It may refer to a job reference number. Or it may be the calibration reference if the watch was used for official purposes, such as a railway time piece. Only the watch maker / inspector who scrawled those numbers onto the back of the watch will be able to tell you the significance.

[watchmaker]

Unfortunately there is no universal protocol for what and how watchmakers leave marks.

The information is generally a variation of the following though:

Watchmaker initials/identifying code
Date, Month/Year, Week number/year
Job number (either in full, or the last four digits)

Less commonly, some watchmakers will have specific codes for different types of work such as:

01=full service
02=Regulation
03=dial replacement

I’ve only known a couple of watchmakers that do that though. Most will only leave a mark when the job was a full service.

[Greg 59]

That is very interesting. So there's a chance that it was previously taken apart back in 1974 maybe?

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[77T]

Welcome to the forum.

I agree with Scott that some watchmaker likely put H-74303-N11 on the case back’s inner surface. But such a lengthy string of characters including hyphens is highly unusual as a simple servicing record.

Since you’re handy enough to unscrew it and do a stem/crown replacement, can you take a sharp, well-lit closeup of the inside of the caseback?

It could also be some engraver was told by the original, or a subsequent, owner to inscribe H-74303-N11 for ID purposes.


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[lamnyc]

When I took in my oyster date to RSC NY 30 years ago, they put in a number on the inside of the bracelet clasp.