If you have a Maytag Quiet Series 200, buy a star screwdriver kit. You will need one.
If the quality of your washing steadily goes down, try taking it apart. You will need a star screwdriver, 2 sizes.
Take out the bottom rack. Under that is a shield, take that off. Under that is the arm and attachment, take that off.
Under that is a round "cam" that looks like a pulley wheel with one "screw", take that off.
Under that is a filter. Take it off and clean it out. Then put it back on and reverse the process to put everything back. You will have to do this every so often, depending on how much "food" goes into your dishwasher. I find that about once a month is necessary, even if I try to keep all the dishes scraped and cleaned before I put them in. I mean, come on, what is a dishwasher for if you have to wash them before you put them in!!!