My Kitchen Aid washer will not drain properly. There is standing water in the tub. I thought it was because of an upbalanced load, but after I put it through a rinse and spin cycle with nothing in the washer, it is still not draining.

Previously, it was making a rattling sound from under the unit while in the spin cycle. I took the front bottom panel off, but did not see anything unusual while it was spinning, only heard the rattling noise which was hard to pin point where it was coming from exactly. Now I don't believe the spin cycle is spinning fast enough to create this rattling noise.