The key bushings may have swelled as stated above but there is no "all you do". They would have to be properly spaced to travel freely, and by properly spaced, means, too much and the could wobble and/or try doing it yourself and you can crack the key at the bushing as well as cause various other problems. These things have to be handled gingerly, so if you go it alone, be real gentle, young jedi. Some things can be handled with a little investigation and some gumption, and we get lucky, but sometimes we break things. Good luck.