Exercising your legal rights will require you to prove the failure is due to a defect in the equipment's manufacture or design. This is frequently a difficult burden. Doing your homework before you buy may spare you the hassle. You know that regular maintenance is important to keeping your regulator in top condition. But unless you read the warranty card, you might not know that having it serviced annually is often required to keep the warranty valid.
Warranties differ, of course, so read the fine print.
You may even get a pleasant surprise. Some regulator warranties will provide, at no charge to you, the parts that should be replaced annually.