I don't have experience with the Q24, however I have had an Innova for 8 or 9 years and I remember changing the check spring only once, maybe twice. It wasn't broken when I changed it, but the tension had become inconsistent. Changing it (on my machine) is easily done and doesn't require a technician. Since you've had so many failures in a short time, it would seem to me that something else might be going on. You may be right that someone got a bad batch of check springs. Ask the technician who has been working on your machine if others have complained about the same problem. Good luck!