I couldn't really play it. It was running very slow and when I pull the lever, it moves a little then stops, and if I hover the mouse over it and keep up with it, then it slowly moves, but if I just pull it down it stops.
So I think what you have done is made it while LMB held down, lever follows mouse, but if mouse moves away from lever, it stops. so at low FPS like on my system, it gets left behind almost immediately and this breaks it. Also, the lever moving very very slowly and so I think that you have it moving a certain amount each frame, instead of a certain amount each second, and so it becomes framerate dependent.
maybe grab screen_y of mouse on LMB down over lever, start tracking mouse pos, stop tracking when LMB released, and on each frame update lever to the current mouse pos Y value or something.
the help text with the arrows was nice. I thought that there was no sound but it was just very quiet so I think if you can normalise all of your SFX to -0 db or maybe but a compressor on the audiobus?