The wire with the rib on the brass peice goes in the middle (with the rubber on it) and the other is the one that gos accross...
Sometimes they can get a bit tricky and wont turn off, the best way I deal with those is to have it running, With the thrtttle in the stop position reach in behind the carby and push the center wire, and wiggle it a bit until the engine stops.
SAFETY NOTE: make sure while fiddling with the ignition wires not to stick your foot under the mower, its easily enough done and even with steel cap boots it hurts
