The handle of the pressure lever is too hard, mainly because the sealing ring in the valve plug is faulty, and the surface of the sealing ring is not coated with lubricating oil during installation, which leads to high friction and makes it difficult for the valve plug to move up and down.
The solution is: remove the exhaust valve, remove the valve plug, apply food grade lubricants on the surface of several plastic sealing rings on the valve plug, and then reinstall. Try again at this time, and the feel of the compression bar will be much smoother.