My woofer was crackling and I was looking for a economical way to fix it.
Apprehensive at the beginning to open it up. But just take all the many screws off and the speaker is held in by four Phillips, use a short phillips to remove. Tenvox 4ohm/20 watt model.
I went to electronics store with my speaker and they matched me up with a 4 1/2" rubber/foam surround for $2 CDN. It was a perfect fit.
I used a lino cutter to get the black cardboard surround off, use whatever works best for you, razor, pry tool etc. Just take your time, it will loosen and come out. Clean/ scrape as required.
I used auto RTV silicone to glue the rubber/foam surround. You can use Weldbond I was told also.
I chose the silicone as it was flexible. Use whatever to to apply. I used my fingers.
First, glue the surround to the top of the cone. You can reverse the rubber/foam and glue to bottom, but much tougher. Glue on both surfaces. Let dry, 2 plus hours or longer the better.
Second , I stuffed some newsprint inside the cone to prop it up and glued the rubber/foam and mating metal surface. Take newsprint out. I applied thin bead to front edge of rubber/foam surround/cone for added strength.
Last, I glued the cardboard surround on and turned speaker over and put a couple of books on top to help set. I advise to set overnight.
That's it. I plugged into car to see woofer working before I installed the back.
This fix only work if your rubber/foam is deteroriated as in my case.
Hope this helps someone. Remember to get the 4 1/2" surround. If you cannot get one, I can send you one at cost.