An evaluation & repair by Canon will most likely cost you more than the body is worth (about $200-$220 in VG to excellent condition), but, in leiu of repair, they may offer you a deep discount on a refurbished replacement. You can check with them using the information at the link below.
United camera, used by many camera makers as a regional warranty service, is a less expensive alternative with a nice warranty. You can get an online estimate at the following link.
Note: The standard "rule of thumb" is if the repair cost is greater than 50% of the value of the camera, it is not worth it. A good used or refurbished T1i body can be purchased for as low as $135 - $225 online
Please keep in mind that my diagnosis & solutions provided are directly dependent on the accuracy of your description of the problem. As with any "do it yourself" fixes, success is a "team effort", since I can't see or touch the camera, and relies on the customer's manual dexterity and ability to follow the instructions well.
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