According to CLIA '88, when must equipment be recalibrated?

Recalibrating equipment after a major repair is a crucial practice to ensure accuracy and reliability in laboratory results. When equipment undergoes a significant repair, the components responsible for measurements may have been disturbed or replaced, which can affect the precision of the equipment. Therefore, recalibration is necessary to adjust the equipment back to the manufacturer's specifications and validate its performance.

Additionally, CLIA '88 regulations emphasize the importance of maintaining laboratory equipment to ensure that any diagnostic testing yields accurate and precise results. This practice also serves to uphold the quality of laboratory operations, contributing to overall patient safety and care. Regular maintenance, including recalibration, is a vital part of standard operating procedures following repairs to maintain compliance with regulatory requirements and industry standards.

The other options suggest intervals that do not align with the specific context of equipment maintenance guidelines following significant interventions or repairs, which is why they do not represent the correct approach outlined by CLIA '88.