Without seeing the sails it is hard to say, but more likely than not they are blown out, or poorly cut to begin with. The bad news is that there is no really good way to restore a sail. There is a lot of hype around various methods to improve older sail cloth but these techniques really are not all that effective since they merely lock in the bad shape and you can build a new sail for what it takes to properly recut an older sail. Your best bet is to try to buy a new sail from a quality larger loft using one of the deep discounts at one of the fall boatshows. Typically in an apples to apples comparison, the larger lofts will be in the same price range of the so called bargain lofts only with more sophisticated cutting patterns and better fabric testing. The good news is that you will be stunned at how much better and more comfortably your boat will sail with new sails.