Complex sentence: Gaynor left in 1981, to be replaced by former Gillan/Broken Home drummer Pete Barnacle, who was replaced by Bryson Graham during the recording of the next album.
Split into simpler sentences: Gaynor left in 1981, to be replaced by former Gillan/Broken Home drummer Pete Barnacle. However, following several live dates with the band, Barnacle himself was replaced by Bryson Graham during the recording of the next album.