When does Marcus Welby, M.D. return?

Marcus Welby, M.D. is an American medical drama television series that aired on ABC from September 23, 1969, to July 29, 1976. It starred Robert Young as the title character, a family practitioner with a kind bedside manner. James Brolin as his partner Steven Kiley, a younger doctor; Elena Verdugo as Consuelo Lopez, Welby and Kiley's dedicated and loving nurse and office manager. At its second season, it ranked number one in the Nielsen ratings, becoming the first ABC show to top the list.