I too like Jim Martin's works. His familiar Gary Gnu voice, his terrifying M.T. Promises voice, the alien Baffle, and how he took over as Edison when John Lovelady left the show.
I also remember how Jim did some guest puppets on Captain Kangaroo.
I remember the times on Sesame Street where he voiced Preston Rabbit and the Great Blecchini. These days, Jim will pop up with a one time Muppet like a monster, a sports announcer, or a wolf.
And I too liked Jim's performances as Ben and the Green Piece Police Captain.
These days, Jim is mostly a director. He directed some episodes of the Puzzle Place and some Between the Lions episodes.