I have been following this thread with some interest, as I have a 11801A that had dead TB NVRAM, and a 11801B with all (still) good OEM NVRAM and batteries.
I don't think there are factory only cal constants stored in any NVRAM, here's why: The service manual for all these instruments describe how to diagnose and replace these batteries and NVRAM devices, without caveat about calibration after replacement.
Also, all these boards were FRU, or Field Replaceable Units, so that repair could be made via board swap.
I think all relevant calibrations take place from the menu items.
