Need advice on Speaker Troubleshooting

I have this speaker that I use for music gigs, but when hooking everything up one noght, it did not want to work. I got some free time and I opened the speaker up.

The speakers moves freely and there seems to be no corrosion almost brand new.

I would believe the speaker needs to be between 4-8 ohms but how realistic is a 20mOhm speaker?