It has been a long time, but I recall removing both fenders and then using a thin, cheap drain snake (from the dollar store) to scrape out the area. I also used a yard stick through the vent holes. The secret is to get as much moving at the end otherwise the debris tends to just build up. Eventually I used water to float out what didn't come with scraping, then a leaf blower to get out that which wouldn't float. And, yes, you will get debris in the car! I've used magnetic strips and window screen to cover the area when not driving. It helps a lot.