Sorry to disagree, but weldon #16 is not the answer here. Weldon#16 is simply acrylic resin mixed with solvent, and does not add appreciably to the strength of a joint. It works okay for repairing cracked acrylic pieces that will not be subjected to pressure.
The key here is to determine if the flaw was intrinsic to the joint from the beginning or if it appeared under pressure over time.
