To address a substantial loss of performance in a production line, it’s crucial to first understand the root cause of the problem. OEE (Overall Equipment Effectiveness) is a measure of manufacturing productivity, and a 10% drop indicates a significant issue. MTBF (Mean Time Between Failures) and MTTR (Mean Time To Repair) are metrics related to equipment reliability and maintenance. A decrease in MTBF and an increase in MTTR can both contribute to lower OEE. By investigating the underlying issues causing changes in these metrics, one can identify specific areas for improvement, whether they be in the processes, equipment, or human factors.

References: The answer is based on general quality management principles that focus on problem-solving and continuous improvement, which are core components of the ASQ Manager Of Quality/Organizational Excellence body of knowledge.