a. Cracking. (Sun Checking) Cracking, or crazing may not be serious if only the outer cover is involved and the fabric is not exposed. If necessary, repair on site with rubber cement where cracks are minor. Cracking where the fabric is exposed and torn, indicates the expansion joint should be replaced. Such cracking is usually the result of excess extension, angular or lateral movements. Such cracking is identified by: (1) a flattening of the arch (2) cracks at the base of the arch, and/or (3) cracks at the base of the flange. To avoid future problems, replacement expansion joints should be ordered with control rod units.