Complex sentence: Follow-up singles were not successful, and the group lost its major-label status in 1980; thereafter, they played on hits by PRT and Tooti Fruiti, and called it quits in 1986 after keyboardist Roy Davies died.
Split into simpler sentences: Follow-up singles were not successful, and the group lost its major label status in 1980. Thereafter, they appearded on the record labels PRT and Tooti Fruiti, but called it quits in 1986 after their keyboardist Roy Davies died.