My experience has been the same as Dunster's. I also have an Innova and can change it myself. One of the problems I first noticed with the Bernina longarms is that you can't self service them, a major inconvenience IMHO. Many longarmers change the check spring regularly. I don't unless there is a problem. What you describe sounds like there is another problem as Dunster mentioned or perhaps a faulty batch of check springs are in the supply chain.