Adrian,
Perhaps you can help me with a box call problem. I had an old Grand Old Master which was one of my two favorite calls (the other being an old Lynch Foolproof). I made the mistake of letting my wife use it when she started to hunt, and when I saw that there was no chance of getting it back, I bought a new one.
The new one not only does not sound as mellow as the old, but when I cut, the spring "boings". I have tried varying the tension, but the spring sound is still there. Do you have any suggestions?