Complex sentence: Harrison having left, Johnson and Woods toured the UK in 1976 with six musicians as "Chairmen of the Board", but they were merely trading on past glories and broke the act up immediately after, Johnson having signed for Arista Records as a solo artist.
Split into simpler sentences: Harrison having left, Johnson and Woods toured the UK in 1976 with six musicians as "Chairmen of the Board", but were not as successful as before. The act was broken up immediately afterwards, Johnson having signed for Arista Records as a solo artist.