[Public-List] Cabin light overloading circuit

[Brent Higgins via Public-List]

Question #2 for the day: I have old cabin lights that are mounted on the forward bulkheads above each settee (wooden base, a little swivel light with 2 metal connectors and the light shade is on a little wooden dowel). All lights are on one circuit, and all but one work fine. The starboard light fixture, when under load, surges from 10 amps to like 45 before the circuit trips. I am using the same bulb in each of these light fixtures, so I figure it is not the bulb. While I am trying learn as quickly as possible, I do not know really anything about the electric system on my boat. Any ideas? Is it as easy as just replacing the fixture or do you think it's a wiring issue? 
Thanks,
Brent