There is 34410a schematics floating around (attached here) who is maybe 85 -90% of the same technology, there is none for the L4411A and none for the 34411a
you have a thread here with picture wich i contributed
https://www.eevblog.com/forum/testgear/agilent-l441a-multimeter-teardown/The main psu is based on a MSC Lx ic .... you can find the spec sheets, it work with the red colored xformer put on the frame to give +18 -18 and a 5vdc to the analog part
and you have the other smps module under the flat cable ....
And pls dont rush to change parts to change parts ...... if not send me the meter ill check it loll, i had one of theses not too long ago and now im on a 34410a, i needed buttons loll
Fully controllable with the old agilent dmm software, and some R&S visa drivers ( better than Keysight )
There is TestController who could control it, but you need to define some coding to properly use it.
It would not be a problem to change this smps with another of the same specs, just take one who can go up to 240 - 265 Vac .... like some meanwell, traco, avoid china crap
traco TPI 50-112A-J .... and they dont cost a fortune, mmmm sure slightly expensive over china crap loll
sorry i did not want to insult you in any ways by the way ...