Complex sentence: Vassy left the group in 1972 after "The Ballad of Calico" album (replaced by Jimmy Hassell) and went on to work on both a solo career and as a session musician.
Split into simpler sentences: Vassy left the group in 1972 after "The Ballad of Calico" album and was replaced by Jimmy Hassell. Vassy went on to work on both a solo career and as a session musician.