I got a case of 3/4" Topaz brand emt connectors, and the locknuts were all brittle like candy. You could take one in both hands and snap it in half. You'd get about two taps on it with a screwdriver and pliers, trying to tighten it, before it would snap. Of the ones that I did get successfully tightened, when I went back to pull wire, I found a good many of them broken and laying in the box. They must have snapped over time. Last time I ever use Topaz fittings.
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.
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