Scrub brush, a bucket of Mr. Clean, and plenty of towels.

The most important part of keeping build up from happening in the crevices is to always make sure the mop is clean when it hits the floor. We recommend a bucket of cleaning solution (do not use to much detergent as this can build up as well or leave a sticky residue for dirt to stick to), then each time you dip make sure you have rinsed the mop in the sink first, not in the bucket. Only a clean mop should touch the floor. To remove the existing build up you will have to scrub with a stiff brush. Also, most cleaners say they are no rinse, but I always recommend a hot water quick rinse to remove any lasting soap or dirt. A steam mop can also be used, but don't forget to constantly rinse the mop head or you will just be spreading dirt around vs. taking it off. Once you get it back to clean you should be able to maintain it easier following these steps. Happy cleaning!!