When I first got the scale I put my Martin Vision on it and it read 50lbs, as marked. My set-up to pull it was a little crude but seemed OK. I knew my new bow was heavier than the Martin. Last night I measured the Martin at 44lbs. on my tiller set-up. I measured my new bow at the shop with an Easton digital scale and a spring scale and they both said 56+ lbs. When I got home my tiller set-up still said 51lbs. I then measured my Gamemaster, that measured 49lbs. at the shop, and it was 43lbs with my scale.
There is only a zero adjustment knob on the scale that is not a calibration. I peeked inside the scale to see how it is calibrated. There is provision to move one end of the spring attachment to different coils in the spring to adjust the rate (like a spring rubber in a stock car). I won't mess with the spring until I explore a replacement scale.
All is not lost, I know several gents who like 56# longbows. I went to my local exotic wood supplier yesterday and bought some Osage, Bocote and Cocobolo so I can make another bow. And another, and another, and another...