Front and rear opening a few feet apart at the top floor(s).
* So does this unit see a high speed demand from short floor to top (5 to 6)?
*Is there a metal fin (vane) which drops high speed to top floor and transition to level speed? If so, maybe move it up a few inches, but be sure to mark the original position.
*Is there another adjustable timer just for leveling duration or time?
*Dirt makes a good point about the up stop limit. Check it out.