Arch is right there is a eccentric screw. it will adjust the height of the lever a little probably plenty to correct the hitting at the bottom.
It's not behind the lever.. take the top off. and at the rear pivot you'll see a set screw on top, Then the pin trough the pivot has a screw slot at it's rear , loosen the set screw. turn the pivot and watch the arm movement.
it's really made this way to take up excess play in that joint but also moves the arm..