The Plexiglas cover is starting to get grungy on the inside just over the trench, how can I clean it?
Open the Box and turn it over. Place the cover on a sturdy flat surface. Apply a light coating of toothpaste, just enough to cover the dirty area. Use an old toothbrush or even a paper towel to rub gently in a circular motion until the cover is clean. Be careful not to apply pressure in a way that could snap the cover. Rinse with a little water. (Most people aren't aware that toothpaste contains a fine abrasive that is excellent for cleaning Plexiglas. It will even remove fine scratches.)