You might want to get some contact cement out and see if you can fix it if it's deep enough to have caused the material to separate. If not, depending on what the woofer is made of, it might be positionally take the woofer out and see if you can pop the dent back into place.
your lucky. if its just a dint pop it in and if there is a rip tape it.
I killed a pair of nice Vintage fullrange drivers from a pair of 1970's wall speakers by steppiing on them ,the paper cones were ripped to shreds. And I was saving them to build a pair of DIY fullrange reproduction speakers. (that plan is ruined now)
I'm reading about others who have dented their woofers, and some have actually stuck a paper pin THROUGH their woofer to pull a dent out.
I know next to nothing about woofers, but the idea of air seeping through a hole while it's operating doesn't seem right to me.
agreed. if you just have a dent, put the grill on the speaker and leave it alone. You don't want to break the seal. If you were that inclined, you could take the woofer out of the cabinet, take the 4 screws out etc.. and push the dent back out from the inside.