When drilling the holes for the joints through the femur sections (the aluminum with hardwood backing), be very careful to keep the size of the hole exactly the size of the bolts (in my case, 1/4").  If you don't, the legs will have a bit of vertical 'slop' in them, which will make things a bit harder when programming.  A drill press would be best for this; unfortunately I don't have one.  Most of my legs are fine, but two are a bit sloppy.

You can mitigate this to a small extent by tightening the restraining bolts directly underneath the coxa joint.  The problem with this is that you have to be careful; tighten them too much and the legs will bind.

I may have to replace the wood in the problem legs and re-drill.