For future reference the manual for your Coffee Machine can be found here.
If your referring to the waste contained which is located under where the cup is placed this would suggest the issue is an overflow problem. If its full up of water (clear) rather than Coffee this is often caused by scale.
Instructing for descaling can be found on page 12 of the manual referenced above, in essence place a descaling solution in the water tank, press and hold both Cappuccino and Latte buttons for 3 seconds.
If this doesnt resolve the issue, you will need to get the unit serviced as there is a blockage in the boiler.
Please let me know if I can be of any further assistance.