Send your Form 1040-X to Kansas City as listed in the IRS instruction book.
Department of the Treasury
Internal Revenue Service
Kansas City, MO 64999-0052
You can also drop off you forms if you have a local IRS office close by.
Although it's not a good idea, IRS will eventually process you return no matter what processing center you send it to.
Send your forms by certified mail with return receipt so you have proof of delivery.