Likely the issue you are having is that the piece that came on your crankset was part of the original package, and not an add-on guard like the true bash guards on the market. Those bash guards replace a chainring on the outside of the crankset versus bolting on to the outer chainring like your 42T guard likely did. My question for you is, do you really need the guard there? Aside from keeping your pants/calf a little cleaner, it's not doing much. The fact that it broke should tell you that it wouldn't be much help in a situation where a real bash guard would help.