Are the negs unsharp over the entire neg? (partial might mean the front is out of alignment -- see if at infinity, the sliding front part with the lenses is parallel with the body of the camera.

Check the pressure plate -- make sure it is on 6x6 and not for 35mm film (you should see "6x6" if it is in the proper place). The film plane is set back a little for when the camera is set up for 35mm film due to it not having the paper backing.

Good luck!