I have a boat trailer for my Sunfish and got it out for the first time this year. The break light on the trailer did not work. A friend pulled it out and used a pocket knife to scrape off the rust. We put it back in and it worked!
That's why it pays off to check the simplest solutions first. It's been my experience that that's what the problem usually is. Or maybe you just got lucky?
I was ready to make a run to the store to get more. I am always up to save a few bucks. Now that I know this is a simple solution I will check this sort of thing.
