Aerial model 5 woofer replacement

I second the recommendation from @hk_fan.

I spoke with Michael Kelly within the past year and, while they did move locations, the business is still operational.  Michael is one of the good guys I have purchased from and very helpful to his customers, IME.  It would be silly to get your replacement driver from anywhere else. 

I agree, although I ended up not buying Aerials, my conversationS with Michael would lead me to believe that he would be most welcoming to the opportunity to help.

The woofer is a 7" cast-frame unit with a damped polypropylene cone, custom-made for Aerial by Vifa in Denmark​.

I agree that you should contact Aerial.  The driver may no longer be available, but they could possibly recommend a substitute.  You might end up replacing the woofer in both speakers so they match. ​​

I recently went thru that with a different brand of speakers and they (the company) wanted $300 for a new woofer X 2 since they said the woofer had changed so they wouldn't sound right otherwise. 

I bought these speakers used cheaply so there was no way I was sinking that much in. I got lucky and fixed it myself with a little glue and some solder.

If not I found a after-market woofer online I would have tried from Madisound. 

You could have it rebuilt. A voice coil can be rewound. Check with Upland Speaker in Cali.