"LAUGHING AT THE PIECES." Doctor & the Medics. I.R.S. "Never been a sinner . . . I've never sinned," sings Clive Jackson in a remake of the Norman Greenbaum hit "Spirit in the Sky." He lies. This English sextet racks up a stack of musical transgressions on its debut LP. The themes lean toward the cosmic, with tales about moons, mustard pots and a "Watermelon Runaway." That might have been a kick, except that Jackson frequently delivers the fanciful lyrics in an ultra-serious, raspy bark that wipes away the whimsy. Meanwhile, intrusive, overblown harmonies add to the sonic chaos while the music tends to lurch around looking for an effective groove to hook into. Doctor, heal thy songs. Please .