Abstract: Retainer apparatus that functions not only to retain a PC board into a channel in a housing, but also to simultaneously guide the board downwardly into a predetermined installation position in which an electrical connector carried by the board is properly coupled to a mating connector carried by the housing. The retaining apparatus includes a rod assembly mounted for rotation about its longitudinal axis, along one side edge of the PC board. The rod assembly's lower end engages a helical guide receptacle secured to the housing, to guide the rod assembly, and thus the PC board, downwardly into the desired installation position, in response to a controlled rotation of the rod assembly.