Abstract: The invention features an assembly for use in a system used to drill a well. The system is capable of receiving a mixture of drilling fluid (e.g., liquid mud) and gumbo from downhole of the well. The assembly has a grating having at least one opening extending through the grating and positioned to intercept the mixture. The at least one opening is sized to block the gumbo from passing through the at least one opening and to allow the fluid to pass through the at least one opening. The assembly has an arm and a motivator connected to move the arm across the grating to remove the gumbo blocked from passing through the at least one opening.