do you have a cal sticker on it, sometimes you can do a reverse search if it was stored at the cal facility, traceable
it only has an Electrical Safety Check sticker by Keysight from July 2023 but that does not have any work order number on it.
Cal seals on the screws are intact.
it seems to be working properly. Passed self tests and ACAL ALL at least 15 times by now. No errors but I am still not sure it is really
flawless or not. So maybe it has a drift problem which needs long term testing? I dont know...
I am not a volt nut and never had a 3458A before and never studied about them so it's all new to me.
I am contacting the seller to see if he knows anything. I can return it if he cannot provide a reasonable answer