If the bolt is stuck in the buffer tube, it could be bent. Probably just needs a new buffer tube. Not sure how someone could screw up the take-down pin, though. I use the KNS pins.
He TIG welded the pin to the receiver on the outside to keep it from coming out. Apparently this thing came apart on him a couple times too many and he decided to do something about it - the castle nut has been tack-TIG welded to the buffer tube too.