By August 1979, the running order was largely complete. Wright completed his duties at Cherokee Studios aided by session musicians Peter Wood and Fred Mandel, and Jeff Porcaro played drums in Mason's stead on "Mother". Mason left the final mix to Waters, Gilmour, Ezrin and Guthrie, and travelled to New York to record his debut solo album, "Nick Mason's Fictitious Sports". In advance of its release, technical constraints led to some changes to the running order and content of "The Wall", with "What Shall We Do Now?" replaced by the similar but shorter "Empty Spaces", and "Hey You" being moved from the end of side three to the beginning. With the November 1979 deadline approaching, the band left the inner sleeves of the album unchanged.