Don - removing the entire lift arm seems pretty dramatic to me when you just need to install the little lock release button assembly. There must be some type of tool or something that could be wrapped around the handle and used to compress the button into the arm, with something over the grip to protect it.
Kraig - Oh Great One, Keeper of the Photos - that little button assembly is only made out of really thin steel, nearly tin like, and it should just peel out with a set of needle nose pliers. Might have to a little bit at a time but you should be able to get it. If that doesn't work then I'd take a small chisel and tap on the edge as if you were cutting the top on the button. If you can get it to partially tear then I think you can peel it out with the needle nose pliers. I would spray it a few times with WD40 or PB Blaster or Kroil or your favorite rust buster.