"The plane has been in service for 12 years and it is in fine shape now."
That's the important part! There are NO 30 or 40 year old airplanes in continuous service that have not had undocumented repairs or maintenance performed on them, unless you bought the airplane new, performed all maintenance and repairs yourself, and kept overly meticulous logs.
Airplane ownership makes each of us a detective! If we want to know the complete history of our aircraft, we have to dig it up. We may not always be happy with what we find, and sometimes should just let sleeping dogs lie! Ignorance is bliss?
