a few days ago, i think i found the reason
for the shading issue. here's a quote;
A vertex may belong to several chains.
In that case, a modification of the vertex will affect all the chains to which it belongs.
Using the same points as vertices of adjacent polygons is important to smooth the colour at the surface of the model (Gouraud shading).
correcting the problem, by "aligning" polygons,
will take a little more work,
but should solve the issue.as of late, i have been working to learn
the polygon alignment process.I am very hopeful this will work.