Central Vac does not shut off

Question

My wife was vacuuming today and when she was finished she hit the off button on the nozzle to off but the central vac still ran. She disconnected the hose from the receptecle in the wall and it still ran. I tried switching the button on the cannister to manual but no luck. Finally I had to unplug the power cord to shut it off. I pulled each receptical in the wall out to see if there was any lose wires but everyone seemed fine.I'm not sure now what my next step should be can someone help? It is a Kenmore Central Vac about 8 years old