Hi Gord, so it looks like those pieces just don't quite align to each other:





There's a gap of about 0.006 units there, that's just a little over the join tolerance. Also there's a really skinny slivery face in that block piece.

To get a piece that will join it would be good to build it directly off of the surface edge instead of from some other curve.

One problem though is that your surface is not trued up to be flat at its end, if I draw in a horizontal line through this point here:



If I then zoom in on the other side over here:



I can see that the surface does not follow that horizontal line, it wanders away from it some:



So before building additional pieces to connect to this surface, it would be good to address that skew and make the surface have a good clean planar end on it.

It's possible to true up the surface by selecting it's end control points and using Transform > Align to line them up so they're nice and straight but it would be even better to look at the curves you used to generate the surface in the first place and make sure that those are trued up from the beginning.

How was the surface created, is it from a Network or Loft? Can you post a file with the curves showing that were used to construct the surface so I can take a look at your curve setup before the surface construction?

- Michael