No power at key

Hi all, my Dart 340/4 speed will not start and there is very little power to the accessories (very dim headlights and very slow wipers etc.) The battery is fully charged and a multimeter shows voltage at the battery connections, starter relay, alternator, ballast resistor and at the "J" connection at the bulkhead. My next step is to check the ignition switch but I don't know how to access/remove it. Would a faulty ignition switch cause the above issues? Any input would be much appreciated.
Thanks, Eljay