Complex sentence: He played his last game for Essendon firsts in 1974 (aged 35); however, he returned to Essendon in 1978, and played an entire season with the Reserves (aged 39).
Split into simpler sentences: He played his last game for Essendon firsts in 1974 (aged 35). He returned to Essendon in 1978, and played an entire season with the Reserves (aged 39).