I was able to obtain a Fluke 732a without any history whatsoever (only sticker with thermistor resistance at oven setpoint

) and so far I have not figured out yet whether it's a bad or good luck...
The good thing is that one of my 3458a's was reading its 10V output as 0.58ppm from exactly 10V which is a good start.
The unit had some problems though due to poor soldering/repairs that was done before me, so I decided to rebuild all the boards (incl. A5).
A3 and A4 are easy, but A5 (reference board inside the oven) is famous to be very messy to deal with.
I clearly had some poor contacts, so I decided to overhaul it as well (CC resistors and also caps).
BatteryObviously, original batteries were completely dead, but after overhauling A3 and A4 boards I decided to give a try to LiFePO4 battery.
Luckily Amazon has a single 24V LiFePO4 battery, so there is no need to put any extra balancers, etc. for multi-battery setup.
Here is the battery I put into test Talentcell 24V 6Ah LF8011
https://www.amazon.com/dp/B0CNLKKL9C?ref=ppx_yo2ov_dt_b_fed_asin_title.
The battery was able to deliver about 5.7Ah in my discharge test (22V cutoff), which is almost as specified (they specify it as deep discharge down to 18V) and is quite a bit more than standard 4Ah Lead Acid.
Obviously you need to tweak R20 and R10 pots on A3 to make sure the charge and float voltages are good for LiFePO4 chemistry.
I put everything together, but have not yet tested it with a battery as I'm waiting while A5 will be ready too.
Here is how the battery looks inside the battery compartment - there is quite a bit free space there.
You don't even need to cut any new holes as the battery sits completely below the top plate and don't touch any metal with its terminals.
