I recently moved in to a college house, and unsurprisingly the previous tenants (current roommates) didn't take too much care of our old Kenmore 665.1772 Ultra Wash. Anyway, we've recently been having some draining problems, none of us have a clue how to fix them, and no one will be coming to take a look at it for two weeks.

The dishwasher can drain completely, if you press the drain button. However, after a cycle it does not drain fully, so our dishes end up being rinsed with dirty water and dried with a large pool of sitting water at the bottom. The only thing we can come up with for the time being is cancelling the cycle after it's done washing, and restarting a rinse. At one point it wasn't draining at all, but after a day soaking and shaking the hose a bit it could drain again, still not fully. Any ideas?