Modify seam point

 From:  Ditto

I am re-doing a Rhino video with MoI, big fun! Now I am at a point where I get some really funky results in MoI with a Sweep2. To be honest, I get the same funky result in Rhino, unless I adjust the seam points of the rails, so I guess this is where it hangs in MoI as well.

Sweeping the bottom rail alone goes without problem, but sweeping both bottom and top rail won't work.

The file is attached for who wants to play.

Is there a way to adjust the seams of closed curves?