I recently purchased a set of Illusion Carbon 8s from a user here and noticed an issue while bench testing. The user has been very apologetic and offered to take the speakers back, however I wanted to make sure the issue was non-repairable.

For reference, here is the speaker that is fully functional:

and here is the same recording, same amp level, on the speaker that is potentially damaged:

When I check both, they meter basically exactly the same at 3.3ohm.

When I attempt to move the cone through the stroke on the speaker that is distorted, there is a noticeable resistance on the down stroke along with what feels like a 'ridge' that it 'clicks' over.

There is nothing visually defective with the speaker, nor is there the acrid smell of a burnt coil. I'm not really sure if there is any way for me to diagnose this issue in a non-destructive manner. Any thoughts from the group?