Hub carriers lock up (501x wce)

[Nopileus]

I'm building up my 501x worlds at the moment, and i'm stuck at the front.

Its the common problem wich the normal 501 and the durga had, but you cant solve it with widening the holes with a drill, because the hub carriers are made of aluminium (wont work, i tried it). It works when the kingpins are 2mm out, but i dont think this will be a solution.

Does someone have a real solution for this problem?