Another tip: you'll find you need three hands to do the voltage measurement. Get a hold of one of those hobbyist bench vises (any vise will work, but in the US, there's a brand called PANAVISE that's my favorite). Clamp the connector in the vise, pins pointing up. Plug in the AC cord and enjoy the (almost) effortless probing! :-)

(profuse apologies for this being an electrical debug thread and not a film camera thread; though, hopefully, the strategy and techniques will be of interest to anyone repairing stuff)