Search on Zmotor here on the forum for leads on where they get the replacements.
As for the Z screw there are two of them so the likelyhood of them being damaged is low.
you might search on that too and see what the thread turn is suppose to be and you can buy it from
the screw company that I remember seeing listed here somewhere.
But unless the Z screw is damaged or bent there really shouldn't be a problem with that.
But you want to make sure you add the B91.1 kit from the only thing that B9 supplies for the 1.1 anymore http://www.b9c.com/shop/accessories/pre ... ooster-kit