During his Boundary Park career, he was unlucky to be sidelined with two long spells of injury, and was also forced to compete for his place, first by Chris Ogden and then by Peter McDonnell.
Injury kept him out for the whole of the 1978–79 season, by which time Ogden had moved on to Swindon Town and Oldham had signed McDonnell from Liverpool.
McDonnell then became the established Number 1, and after playing a total of 109 games over a six-year period, Platt was released at the end of the season, joining Bury in August 1981.
During the latter part of his playing career he had qualified in sports management at Salford University and in September 1986 he again signed amateur forms for Oldham when he was appointed stadium manager at Boundary Park where he was in charge of community use of the new artificial pitch, and supervised the Football in the Community Scheme.
He played no further games for Oldham in this period, and in August 1987, while continuing his community work at the club, he signed as a player with Stalybridge Celtic.