The first 2 things I would normally recommend would be to make sure youre not overfilling the filter basket and to ensure the grounds arent too fine. But since youve already tried these things, the next thing on your list should be to make sure the filter holder is clean. This part of the machine has a spring-loaded stopper that gets pressed up while the carafe is in place to let coffee drip through. If it is stuck with coffee residue and oils, it will result in the overflow youve described. Try cleaning this part of the machine to remove any residues and see if it helps. If youve done this and continue to have problems, I would recommend contacting Cuisinart directly at 800-726-0190 for further assistance.