One of the first steps will be to look at the maintenance records of that engine-- when was the last time is was dye tested and X-rayed. How many hours til or since overhaul? Who did the work? Genuine factory parts or Turkish knock-offs (a-la Value Jet). Facts needed here.
AA Spokesman:
Left Engine: 694 hours since overhaul
Right Engine: over 9700 hours since last overhaul
typical overhaul at 10,000 hours of service.