Complex sentence: He briefly left the show from 1959 to 1962 when he was drafted by the Army but, upon his return to the Music Makers he was joined in the band's rhythm section with fellow guitarist Neil Levang.
Split into simpler sentences: He briefly left the show from 1959 to 1962 when he was drafted by the Army. On his return to the Music Makers he was joined in the band's rhythm section with fellow guitarist Neil Levang.