Dirt and grime will also often collect around the smaller upper nut, that of the hard brake line, making it difficult to place a wrench over it.

This can be carefully scraped away with the tip of a small chisel or a large flat blade screw driver.

After scraping out all the debris in steps 4 and 5, spray the connection with some brake cleaner to remove small particles. You want to avoid introducing dirt in to your brake system.