Help with Arri problem, please
 

Last week I was shooting a seminar and my main Arri 650 fresnel starting to flicker and was making an arcing sound. Later, I pulled the bulb and noticed that one pin was dark (oxidized?) The light fixture and bulb has just a few hours of use.

Has anyone had a problem like this? Any thing that can be done to prevent it? Should I try to tighten the socket or maybe use some sort of electrical connection compound?

It is a fairly common occurrence that the socket and bulb have some problem over the life of a fixture but rare that it happens so early in its life. If it is new enough maybe you can return it to the dealer for repair.
The bulb was probably loose when you turned on the light. One way this might happen is someone tried to put the the bulb in the socket incorrectly damaging the smaller pin hole in the base with the larger pin on the bulb. The bulb can also loosen up during travel so it is a good idea to check and reseat the bulb before you turn it on after arriving at location. Of course most people just turn on the light and see if it works. If you continue to have problems with the light you should replace the bulb and see if the problem goes away. If you are unlucky and the problem doesn't go away then you should change the socket. It is hard to prevent over time but you should be able to solve it when it happens.

You know, I never thought about making sure the bulb is in tight before the shoot. It was on the road for a while. I think I will clean the lamp pin and socket and reseat the lamp.

From now on I will make sure it is tight before I fire it up. I like the Arri design, it is easy to acess the lamp.

Thanks for the advice.