Well excuuuse me! Who’d expect the original “wild and crazy guy” to be a sterling musician? But Martin, whose first album in 30 years is subtitled “New Songs for the Five-String Banjo,” dazzles with his instrumental bluegrass work. Although he features stellar guests like Dolly Parton, Earl Scruggs and Canadian actor Eugene Levy and voices one humorous number, “Late for School,” it’s Martin’s dexterous picking on original gems like “Tin Roof” and “Daddy Played the Banjo” that truly impresses. Not a novelty.