Some ways to troubleshoot faucet problems are to take it apart and clean the aerator, replace rubber washers and to clear the diverter. Badly worn components inside the faucet may require replacement.
If a faucet is spraying water outward, the problem could be a clogged aerator. This is a small screen located at the mouth of the faucet. If it cannot be unscrewed by hand, use pliers to gently remove it, then flush out any obstructions before putting it back on. If the aerator is damaged or too difficult to clean, most hardware or plumbing supply stores sell inexpensive replacements. If a faucet squeaks when used, the problem is often worn-out rubber washers inside the faucet. Most hardware stores sell faucet washer replacement kits.
When a faucet is not flowing freely, the problem often lies in an obstructed diverter. This is a small valve found in the stem of the faucet, removable with a screwdriver. Soak it in equal parts vinegar and boiling water to remove mineral deposits and other debris, then reassemble the faucet. If these steps do not solve the problem or if the faucet's parts are severely worn or damaged, replacement of the faucet is usually the only option.