Originally Posted by
bikeman715
ok, without you knowing it or the shop for that matter , the threads in the crankarm could be bad in the first place. it might be the reason why the shop have it in the first place. over time it sat there until you have a need for it and they saw it and put on your bike not knowing there was some thing wrong with it .
This is a good reason for trashing any part that is not usable right away or at least putting a label on it noting what is wrong with it if you want to salvage any of the parts on it.