F11 issue on Miele Dishwasher

My Miele G 4960 Vi built-in dishwasher is showing error code F11, a drainage fault. It stops mid-cycle with water left in the base. The legs have dropped before, so I'm not sure if this is a levelling problem or a drainage problem. Please diagnose the cause and fix it, not just clear the code. Please check: • Levelling and the legs • The drain hose (kinks, height, connection) • The drain pump and filters for blockages • Whether the sink or waste connection is involved Experience with Miele dishwashers is required. Please include a quote for the diagnostic and repair, and let me approve any parts before work starts.