What style of carpet are you finding the machine hard to vacuum?
If it is a looped carpet setting and finding setting 2 is just a little to high and setting 1 is too low. Maybe a screw that is a little longer may help with the micromatic adjustment.
When I sent my Heritage II in for rebuild They didn't reinstall the same original pedal. No screw in this one. I have a piece of cut pile commercial carpet that needs that fine tuning of the height adjustment or it is like pushing a tank across the floor.
A piece of dense woven plush carpet the adjusting screw is no help in that situation. As you are above the settings it was designed to "fine tune" the height setting.