Ended up with a 5-decade resistance substitution box which I will probably flip (looks like it all works except the lowest resistor (10ohms). I can guess why that's now 70ohms, and hope the switch hasn't been buggered.
It wasn't buggered. The relevant resistor that was different to all the others, and there was a scorch mark on the case above it. Replaced.
All the resistors are 1% and well within spec, so that was a good buy at £5 - and much better than my previous 8-decade box that I promptly unloaded at a good profit.. Might not flip it; TBD.
Also rescued a Fluke 8300A DMM marked as "all nixies work". Without bothering to let it warm up, when my 34410A shows 10Vdc, this shows 10.0002V. The Vac settings look reasonable, the mVdc show 0, as do the ohms settings.
[img sidth=400]https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/?action=dlattach;attach=1269307[/img]
Presumably because it doesn't have the ohms/millivolt module (option 03) fitted.
Neither of mine have the ACV (01) module, one has the 03. Both are dead nuts against my recently cal'ed 8840A. Fluke for sure know how to build a meter!
Not having had time to look for a manual, I didn't realise those were options. Plus there's no indication of installed options on the case exterior. Opening it up shows that, as you expected, the mVdc/ohms option is not installed.
I'll get the manual, possibly replace the blue Philips electrolytics. I suspect the tweaking might be the zero offset and the scale for ranges other than 10V.
Since I got both just because they have nixies, I might have to decide whether to sell the 8300A or 8125A
https://www.eevblog.com/forum/testgear/fluke-8125a-military-dmm-teardown/msg2540730/#msg2540730