There are plenty of warnings about being careful when inserting microbarbs and tightening screws but please be aware that there are one or two weak areas around the frame captive nut inserts that really do need extra care when tightening the screws. Hand tight is not what is needed here, but just beyond finger tight is more suited and to leave these until all surrounding screws have been tightened. The picture shows one such point where the screw was tightened carefully then others tightened after; a short time later a small click was heard and the crack appeared i.e. the stresses applied by the other screws pulling the frame into alignment was too much for this narrow area. Superglue and the surreptitiously applied label mask the problem but avoid this if you can.