Allisons are sweet.
you can repair a tear with nylon stocking, and rubber cement.
But if you want to get serious, take it to a re-cone center, where they repair professional speakers. http://www.speakerrepair.com/
A local music store can help you find a speaker repair person technician.
Most often, people want the foam surround of the speaker replaced. This is the outer ring of the speaker, that sometimes rots away or breaks...
Speaker shops can replace that, for just a bit of cash. Many times, it will make the speaker work OK again.