What causes this?

[Kain91]

Thats not from being dropped. It happens from being fed to much power and the pole glue heats up to a sticky state and the pole dropped. Since the coil freezes it can no longer generate heat and the glue resets

[HumbleDeer]

Not just overheating does it. Any kind of heat cycling or defect. This means that if there was a particularly cold period, it could've cracked the glue.

The best way to re-center it and glue it is to clean off the old glue if you can, and epoxy it back on with shims of equal distance on all sides. But, be warned. There's a chance it'll never be like it was before. 

Edit: I see this a lot on PA cabs that have been dropped. I work in PA, not car audio. 

[out4u]

Update:  well making progress fixing it now if I can just find a recone that'll work to make it better than a paperweight, unfortunelty I can't get the same one since they sold out and never came back since like 3 days after I bought em..