Be careful with Aperture. Just been messed about for a month by the technician there. Ask for a written report of what is exactly is wrong and ascertain if its actually/realistically possible to fix. Put a comprehensive focus test roll through as quickly as possible after the repair, even if they say it's fixed, then make sure you test it again.
I wouldn't go there again for a repair for quite a few reasons in all honesty but I'm also quite stubborn and believe in principles.