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If you can get the flash open without damaging it too much, it's not a tough replacement. Get a 2 watt 100K ohm resistor. Its pretty hefty looking. Touch the leads of the resistor to each end of the Capacitor leads. Hold it with a pliers, not your bare fingers. This will discharge the cap.
The bleed-off only takes a second. Very Important !!! Beware of the polarity when replacing it, Caps only go in one way. The + and - are marked on the PC board and the Cap itself. Also, if the cap is already dead, It wont' have much or any charge in it. Just remember, you'll need to get the exact capacitance replacement, from a good supply house, such as Allied or Newark electronics.