I use two long sheet metal screws. Turn each in a little at a time. That way, all the stress isn't on one. Of the dozens I've done only broke one off (and ruined the carb). Both limiter plastics and collar come out at the same time.
A high quality dental hook works as good as the tool meant for it. Find the one with the most hook at the base of the pick and modify it to a little j hook shape.
Most of the limiter caps have a little tab down the outside edge that lines up with the groove before they'll come out.