Thanks Tom and Raymond for the advice. Two questions from a novice
troubleshooter.
1. I don't have access to a 550 uF, 100 volt electrolytic cap. Tom, when
you say "tacking a radial leaded cap across C1512" to you mean soldering it
on the pads and then checking the AC measurement again. Also, I can't find
C-1512 on the board or in the service manual. The manual is for 465B scopes
with B06000 and up. According to the service manual, all caps on the
horizontal amp are in the 4XXX range.
2. Since I don't have a cap anywhere near the 100 volts, is there another
way to check the cap to see if it is faulty?