u/Future-Appeal-5330

I have this tester, and I need to check the hardness of 17-4. It should be HRC 42-45. The only thing I can figure out on my own is seeing the knob to 150. Can anyone walk me through an the steps? I can't figure out how to set minor load, if I need to zero it at minor, then how much pressure to apply. It's not clear how to release the major load, but I think I push the silver button and rotate the lever on the right clockwise.