That's happened to me and rrlev. The adhesive you ordered is for foam surrounds and I very much doubt it will hold.

I think each voice coil is 2 Ohms. So the sub needs 20+ Amps of current for rated power and closer to 40 for peak power. Hence the conversion from high level.

Interesting there's no dust cap. I like that clean look.

Nice troubleshooting!

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated