[time-nuts] HP E1938A question

[GandalfG8 at aol.com]

I've just received an Ebay purchased E1938A, haven't tested it yet although 
 I do have a 14 day return option, but unlike previous purchases of these  
the serial number label is missing from the rear of the PCB so I have no 
obvious  way of knowing if the crystal is matched to the PCB.
 
Does anybody know if there's any embedded information that can be accessed  
that indicates the serial number of the board, or is there any other way I 
can  check if the crystal and PCB are matched?
 
If not, what issues could I expect from an unmatched crystal and  PCB?
 
Nigel GM8PZR