I'd try another 109mm axle, it's the only thing I can think of that might be causing this (other than the frame being borked).
I'm very wary of throwing much more money at it, kind of a £45 gamble. Was it the bearings or the axle that were stiff going back in?
@Currid started
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I'd try another 109mm axle, it's the only thing I can think of that might be causing this (other than the frame being borked).