If the spring fails on the earlier non ratcheting tensioners I can see this. The ratcheting tensioner was introduced at some point and cannot back off the chain totally without taking the tensioner apart. It is always semi pretensioned by strong non reversing mechanical design.
Have you found the spring available separatly? At least wear of the springs circumferance as a cause sounds reasonable. The spring could be inspected for the wear before making a decision on the replacement. You posted really good helpful information for the members to think about. Good thinking about saving dollars as well if possible.