My native language is german, so close one eye sometimes! ;-)
I had to observe homebrew random and periodic 100pS impulses and so bought old Tek parts because my limited budget allowed not "state of the art" and the low cost caused that somewhat has to be repaired. And so I found this site. Hardest to repair was the 7T11, a tunnel diode did randomly "shut down" and pick off a replacement was a hard job too. :-)
Have fun with Tek and HP and never give up!