I will try to type this out. I was on a service call today, about replacing some bulbs. So go to replace 1 bulb as soon as I touch the bulb it comes on. So I put some white lithium grease on the prongs and it worked about halfway down the prongs. I go to the next fixture and the same problem. The fixtures are about 4-5yr old vista pathway lights. I was told that the type of sockets are the problem. That they have a spring loaded clamp in the socket, so when you move the bulb you get a decent connection. Also even using the grease it appears there is some corrosion on the prongs. Do any of you experts have any ideas on what is going on.