More digging led to my finding this post by Paul Joppa (about discharging 220uF 250V PS caps):
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Re: Building a capacitor discharger - what size resistor to use?
« Reply #1 on: January 26, 2012, 12:07:35 PM »
"Perhaps we should look for a resistor that will survive even if the circuit is still accidentally powered. Let's say you want to use a 5-watt resistor; then since power equals voltage squared over resistance, the minimum resistance is 8000 ohms. The time constant RC is less than 2 seconds, so if you leave it connected for 10 seconds (5 time constants) the voltage will decay by a factor of 175 (e to the 5th power) - i.e. to a bit over a volt. 10K is probably easier to find.
"For a 1 watt resistor, you'd need 40K and it would take 50 seconds to discharge. I'm not that patient, myself."
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So, again, to be perfectly clear, the process for safe cap discharge should go:
1) Power off amp
2) Touch 5W 10K ohm resistor to octal terminal 5 & anywhere on chassis for 10 seconds (please see photo to verify)
3) freely handle alligator clips or leads of any cap in the amp
...or for a specific cap, touch resistor ends to each lead of the cap to be handled for at least 10 seconds.
Is this correct? Thanks for bearing with me.