An unreleased lien is, IMHO, a deal killer when you're looking to buy an airplane.
+1......close your eyes as you sing "Walk Away Renee" and then follow the songs advice.
If you're in love with the plane, you can give the current owner some time to get it cleared up but by no means tender the capital until it's documented to be clean.
If you're borrowing money to buy the plane, any lending institution worth their salt will make the decision for you as they will not position themselves as the second lien holder.
Jim