spring perches, castle nuts, and cotter keys

[rer_239]

anybody else have problems with these? got new of each, the problem is that the cotter key fits just fine on one side of the castle nut but it won't slide thru the slot on the other side of the nut. is it because the new ones are made off shore and there off just enough so its not straight? do i have to replace them or is there another way to secure the perches?