Check to see if stair was installed square.
The bolt attaching long arm of the spring arm to the side of the ladder may be too tight and needs to be loosened 1/2 turn. Also put a very little oil on areas where metal parts are rubbing against themselves.
Depending on the amount of use, some parts will get loose from wear. These parts may be ordered from the factory. You will need the following information: panel door size, date on stair, number of treads or steps in middle section and whether the treads are painted.
The ladder was not trimmed to the correct length. A properly trimmed ladder must show all sections in a straight line. See installation instructions for the proper procedure.
American Stairways offers many sizes, duty ratings, energy saving, and code compliant options to meet your requirements. Take a look to see which model works best for you.