Trying to get to Ignition Lock

So ...73 Duster auto ....I'm trying to change out the ignition cylinder lock and stuck at this part (see pic). Pulled the first snap ring so the cover "should" slide out towards me so i can get to the next part....damn thing spins but i'm yanking on it and it doesnt budge. Do i need to remove anything else! All screws have been removed as far as I can tell. Been following the instructional thread step by step. Tried to remove rubber ring but seems to be well attached, dont want to destroy it unless i have to.