Mr. Carlson delivers very polished videos, which I usually really appreciate, as he has a lot of knowledge about vacuum tube devices.
But he also polishes the YT comments, i.e. he blanks / censors unwanted negative comments. This I really dislike.
So here is a copy of my three times blanked out comment about his latest repair video, in which he really has very little clue about the subject.
'Sorry, that repair / DC range calibration was not done in a qualified manner.
E.g., it was not necessary at all to replace that nominal 22M, 10% resistor inside the DC probe, as its drift is exactly compensated by this 1V range trimmer alignment. In fact its value or its drift has practically no influence on either DCV range. This is evident, because the change from 26 to 22 MOhm did not change the alignment of the 1V range at all.
Also, the replacement of the other range resistors could have been done in a more clever way, e.g. it is necessary to trim only one resistor to get this upper 68.3M resistor, instead of replacing both. It's missing also the important information, which type of resistors you've used as replacement. So did you use modern 1% thin film resistors, or crappy/unstable carbon resistors out of your junk box?
Back then, in the Airforce cal lab, I repaired lots and lots of these hp410Bs, so I really can't appreciate your repair methods.'