we had a bad run of thresholds, because we switched welders back in september. im willing to bet that all of the TSIs that you broke were from that welder. we brought back our original welder, who's much better at what he does. i would suggest you buy a newer TSI directly from us (or from Sky High, they just got a new batch of 22"s in stock), and see how long it lasts you. i feel like it would last you longer than 3 weeks, for sure. if it doesnt, then idk what to tell you other than to try something else.