"Dave"
"Phil Allison"

The first thing to check is all the filter and coupling electros in the
vertical and PSU for the vertical.

You need an ESR meter or lotsa luck.

Guess I'll need lotsa luck. What does an ESR meter actually measure,
pray tell?

** It will tell you if an electro cap has or is about to die of old age.

Does this by measuring its internal resistance or ESR independent of actual
cap value in microfarads.

ESR = Equivalent Series Resistance.

http://en.wikipedia.org/wiki/Equival...nce#Capacitors

..... Phil