Have you checked the calibration of the machine? I bought a same model and the mass of the weight was nearly 70 grams too high (diameter is 68 mm and it should be 66 mm). I drilled six 6,5 mm through holes to the weight to fix the problem. The tension depends on the angle of rotation of the gripper. If the gripper is in a horizontal position the tension is +0,7 kg and in a opposite horizontal position the tension is -0,7 kg. In a downward position the tension is ok. I checked the tension with my digital fish scale.
The machine comes with 2 bolted on weights. You need to just use one. It's easier to re-mark the tension scale strip than to drill holes in things. The idiot I bought the machine from knew nothing about the machine. So i nearly tensioned my MP99 to 50LBs.
In won't call the previous owner an idiot. It's down to the new owner to re-cal the machine, especially if it's 2nd handed. Maybe the previous owner was using that for racketball/tennis racket?
Please respect other individual. Imagine how you will feel, if you ever make a mistake, and ppl talking rudely about you in the public.
If the weight is too heavy you loose the lighter part of the scale. Challenger has a tension range 7...37 kg and I don't want to loose any of it's lighter part. I think it's harder to clue the new scale to the rod than drill those six holes to it.
i stuck masking tape on top of the factory scale, and drew my own scale after calibrating the machine with a fishing scale. I can string from 13LB to maybe 30LB tesion. That's about all I need. By the time I can handle 30LB tension on my racket, I would probably be world number 1. By then the string machine makers will throw free machines my way.
