Originally posted by IchabodCrane Alex, if there's any way you can repeat the horizontal shot with the camera upside down, that will probably tell you if the actual center focus spot is really below center.
Alternately (and easier!) -- maybe you can use a rigid item with fine detail that can be propped with top toward the back (as in the shots you've taken) and also with the top toward the camera (image taken looking from underneath). If you get front-focus in the first case but back-focus in the second case then it would confirm misplacement of the center AF spot.
I asked the repair guy and he did the horizontal shot with the camera upside down. The picture still shows similar front-focusing. So I guess we can rule out the possibility that focus spot has shifted from the center.
I am running out of guesses. Any help would be appreciated.