I have a Rittenhouse model RCM-3 all transitory Intercome system for my 1962 house. I would like to replace it with a new model of intercome that is compatable with the sytem. The speakers in each room ( about 5 units) are model SR-4 . The radio still works but lot of static and the buttons are not functional. I have a door bell chime too which can be heard very faint. I am assuming the wires are all working but need to be repalced by a newer generation of intercome system.Please advise.