Door will not fully close. Door will slam just before closing. Door will have little or no control in latch speed range. Door will “bounce” back after closing against frame.
It is important that the screws be tightened at the same time; not one fully and then the other. This will cause the arm to wobble on the spindle shortening the life of the installation and the arm.
Also – Insure arm alignment screws are secure on the end load application.