i will assume you understand what an "open" and "short" are and what the multimeter displays for both. 0.L = open and 0.0 = short.
here is the capacitor in a 6 pin. it is the big silver "can" at the bottom with the 2 green wires.
take the cd out and remove the cover.
lay it down with the black connector to the left.
about 1/3 the way up on both sides, you will see "C8" on the circuit board.
take a wire and connect these 2 terminals then remove. this puts the CAP at "zero". when you connect the multimeter it puts a small charge on the CAP, so "zero" the CAP each time you check it.
put the leads on the 2 "C8" pins. the meter display may jump around but then it should start counting up. what this is indicating is the resistance is increasing as the multimeter charges the CAP. if it shows zero (0.0) then the CAP is shorted and bad. if it does nothing (0.L) then it is open and it is bad.
the 3 pins are not that much different. mainly just the triggering circuit. the boards look older along with the components.