We pull the old door and track first, check the opening for square, and reset the jamb hardware if the years have shifted it - more common on Carol Stream's 1980s framing than you'd think, since builder crews worked fast and didn't always shim evenly. New track goes in plumb, springs get sized to the actual door weight rather than reused from the old setup, and we test the balance by hand before the opener ever touches it. For insulated doors, which we'd point most Carol Stream homeowners toward given the cold-winter climate here, we check the weatherstripping and bottom seal fit against the slab, since an insulated panel does nothing if the seal around it is loose. Opener mounting and safety sensor alignment get checked last, after the door itself is hung and balanced.