Complex sentence: Lead guitarist Peter Dickson left the band in February 1979 and returned to Australia and was replaced by New York Guitarist Justin McCarthy who stayed with the band until they broke up in 1984.
Split into simpler sentences: Lead guitarist Peter Dickson left the band in February 1979, and returned to Australia and was replaced by the New York based guitarist, Justin McCarthy. He remained with the band until they broke up in 1984.