Hmm... I don't own this iron, but I had one with a similar self-clean system before.
Do you have the steam turned off when you heat it beforehand? It needs to be off for the self-clean to work. Also, are you keeping the button pressed down as you jiggle? There should be lots of bubbling and rumbling sounds as the water hits the dry, preheated steam plate. The whole canister should drain if you keep the button pressed down. Lots of water will evaporate at first, but then it will start coming out the holes in the sole plate.
If the manual says not to use vinegar, I believe it - the metal innards can react with the acid.