Don't forget about "soak", also known as dielectric absorption or
dielectric hysteresis. In some capacitors, particularly electrolytics,
charge "soaks" into the dielectric and can take from seconds to days to
work its way out. The result is a "discharged" capacitor that seems to
spontaneously recharge itself. (One story I heard during my broadcast
days was someone who put a screwdriver across a "discharged" capacitor.
After he picked himself up off the floor, he found just the handle of
the screwdriver. He was lucky his eyes weren't hit with molten metal.
You'll often find large capacitors stored with a shorting wire across
them -- a good idea.) I recommend leaving a heavy cliplead in place
across the high voltage capacitors for the entire time you're working on
the unit. Put some tape over the on/off switch and/or a tag on the plug
to remind you to remove it before turning the power back on.

As a side note, the aquadag coating of a CRT is notorious for this. I've
gotten a healthy bite off a CRT the day after it was discharged for an
hour or more with a cliplead.

Roy Lewallen, W7EL