Airing on Hallmark Movies and Mysteries. From Happy Days: Pat Morita, Erin Moran, and Donny Most. From Mork and Mindy: Conrad Janis. From Laverne and Shirley: David L. Lander and Leslie Easterbrook. Ironically Scott Baio was a regular on the first two seasons of Diagnosis Murder, but was long gone by this point near the end of season 5.