i had same problem and it was wiring, corrosion and something else too. WATER. pull the globes out, poke your finger around in the lense (where the light globe usually goes) and make sure there is no water in there. If there is, you may need to drill some tiny holes to create a bit of ventilation and speed up the evaporation process. water gets in from the condensation build up on those cold days and nights, not coz the lights are leaking.