If the optimal auto focus settings of the camera body are disturbed due to eg. impact damage, the auto focus system must be reset according to the manufacturing specifications.
The camera body is testet using the production AF test equipment. Necessary calibrations and adjustments are made. These include mirror alignment, focusing screen alignment, and calibration of the AF sensor. In addition, the rear interface locking mechanism is upgraded to latest version in order to secure a tight fit of the digital back / film magazine. A functional check of the body is made and firmware is checked and upgraded if necessary.
When these tests have been completed, the unit is ready to be returned.