First thing I would do is to get into the attic space and have someone you can trust to let the stairs up slowly. Look as it closes to see if anything is rubbing or binding. After it is closed and still has the gap--carefully grab one or both springs and see if you can pull on them to close that extra inch. If you can you may need to adjust the spring tension. Some units have an adjustment, some don't. Pay close attention to the hinge end to see if something is binding there. Also note from the hinge end to the open end if it may be closing tighter near the hinge end and binding before the open end closes. Just before this stair closes, the panel you see from the floor should be almost parallel to the framing for the stairs.

 

1 1/2" is a lot. I've installed them where they aren't quite evenly closed but not that much. Thurman's advice is good, there must be something preventing it from closing, unless the stairs themselves are warped. Also, check the installation to see if all sides of the stair frame are level/parallel with each other. It might have been installed crooked

 

My pull down attic stairs had a 2 inch gap in the closed position. I was able to fix this by simply moving the stair assembly closer to the cover hinge.

There were 6 brackets that connect the stair assembly to the plywood cover, 3 on each side. The middle bracket on each side had a slotted hole for the fastener holding the plywood cover to the bracket.

I loosened all 6 fasteners, then pushed with as much force possible on each of the 2 brackets with slotted holes toward the hinge, one at a time. I used a large screwdriver to push on the brackets. (Anything with a handle suitable for pressing against an object such as a hammer will work.)

The fastener in the slotted hole was tightened while pushing the bracket toward the hinge. Repeated on the other bracket with slotted hole. Then I tightened all the other fasteners.

Problem solved.