Earlier in their life, they had issues with new carbs that would mysteriously start to show metal in float bowls. The cause (From Barry himself) was drilling aluminum. They would drill a certain passage, and the aluminum bits would be compressed at the bottom of the passage by the drill. After the carbs were run, and vibrations from the engine and the road, they would vibrate loose. Barry and crew figured out the problem, and would run a smaller bit down the same passage afterwards to break up any compressed shavings loose so the passage was clean.