CNS Carbs Breaking

i sold my murray monterey project to my buddy. it was going fine for a couple days and he wrecked hiself somehow..roadrash the whole 9, not a scratch on the paint but bent the holy **** out of the forks and twisted them backwards ever since then its been one thing after another with this bike..the kill switch wouldnt work, the fender busted off and rubbed the back tire,the magneto went out the, carb just popped off .and after putting it back on and tightening, he rode it around for a while and it flew off again. this time the metal that holds the screw popped off, broke off about 1/2 in below the screw on the outside. so i ordered him a new one, and about 2 hours later he called and said it had broken off again, in the same spot an flew off. gas bike says they might warranty them if we send em back but then again they might not, depending on what they see. what could be causing the case to get broke like that? and in the same spot?

my buddy has another bike its an old firestone 500,.its got a 48cc with a NT carb on it so we swapped it to the other bike which has a 66cc..didnt really run very good and wouldnt idle right, so we swapped the intake tube as well and still he says theres no power, i get plenty of power out of my NT carbs whether theyre on a 48 or 66, the NT ran great on the 48cc but crappy on the 66.. cant figure out why. the 66cc ran great with the CNS carb too until it flew off
the rep at gasbike said it could be due to vibration from it not being mounted right or because of the bike not being built right, but i hardley noticed any vibration at all on this bike ever since i built it its been very smooth and quiet