Check if the clips (A, B, C, D) are damaged or stress-whitened, and if necessary, replace them with new ones.

If the old extra window is to be reinstalled, use a putty knife to scrape off all of the old adhesive, the clips and the rubber dams from the extra window. Clean the inside face and the edge of the extra window with neutral detergent where new adhesive is to be applied. Make sure the bonding surface is kept free of water, oil and grease.