Lockheed didn't take that long to fix the turbo system problems once they could isolate it. It was well masked by the high-aromatic fuel used in Europe and they didn't know that until someone sent a sample home. They found the issue in the next week on the test stand and everything was corrected with a couple if month of that. The issue wasn't a single thing ... it was intake tract combined with incorrect jetting for the fuel being used combined with poor pilot training.
Once they knew the fuel was different, I don't think it was very long until it was ALL fixed. Total time was around 9 months, but 7 of that was spent looking around without any knowledge of the difference in fuel.
So yes, it took some time ... but not all that long once the issue were understood. I once heard a talk on that from a fellow who was there, and his comment was, "Who knew they would be running different fuel? We certainly didn't know!"
Whether or not he was spinning a yarn for a good story, I can't say but, in the end, it DID get fixed.