Unless you are adept at upholstery, I would suggest finding a shop in your area that does this type of work. A new seat is probably in the vicinity of $700-800 thru dealer. The seat has to come out and the spring pad inside the seat has to be removed to get at the cushion material. Find a pro. If the outside of the seat is still in good shape, you will save some money over a new item.

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.