On my K2k voltage measured across the VR109 was 18.6V, so I replaced it with regular small glass 16V zener diode. Now I am measuring little less than 17V across it. Diode is getting quite warm, and I will probably replace it with bigger 1W one.
I have some 0.01% resistors for testing, and my meter is spot on on low ranges. But on higher ranges it reads little higher than it should, 100.001k resistor reads as 100.015k. It can be simple calibration issue, or maybe there is fault somewhere... I must do some more tests.
Then there is also noise issue visible if I disable filtering. Last digit or two randomly flickering up or down. I can't find some pattern in that behavior, sometimes it is more and sometimes it is less noticeable...
There are some more issues, I will document them after more testing. But I think they are related with calibration.
I've dumped original content of calibration eeprom so I can safely play with calibration.
My K2k passes self test without error.