Complex sentence: For many years, the majority of the show's episodes were feared lost, with only 12 episodes in general circulation among collectors until the late 1980s when more than 80 episodes were discovered, comprising the majority of the series' run.
Split into simpler sentences: For many years, the majority of the show's episodes were feared lost, with only 12 episodes in general circulation among collectors. In the late 1980s, more than 80 episodes were discovered, comprising the majority of the series' run.