I am experiencing a problem with some Hadco Pathlights that we installed just over a year ago. The fixtures are a Hadco Model MUL4. They take a 20watt bi-pin lamp. I have had repeated calls from the homeowner that certain fixtures are not operating. What I have found is the lamps seem to be almost out of the sockets, or they are not making very good connection with the fixtures' sockets. If I simply tap on the top of the lamps, they come on and function properly. Is this a Hadco malfunction? Could the lamps be coming loose due to vibration, etc.? I am baffled by this one!