In a crank type stringer (Neos, Gamma 5003/6004, Pro’s Pro Comet/Pioneer) the spring that determines the tension, remains pre-compressed the entire string job and gets compressed even more when the string is pulled. In addition, most stringers do not set back the tension knob to the minimum while not using the machine. The result: the spring is under tension the entire time, becomes inaccurate over time and therefore needs to be calibrated or replaced regularly.
The EZ Pull Tensioner in MiStringer also uses a spring. However, rather than compressing the spring to set the tension, the spring is moved along the lever, which alters the tension without the need for compression.
The only time the spring in MiStringer gets compressed is when the string is being pulled. Even then, the compression is only about 10 to 20 percent, which has no impact on the durability of the spring at all. For this reason, the spring in MiStringer does not need calibration or replacement.