Irregular spacing between section title and first paragraph

["Paul Lenson" <lenson at pcigeomatics dot com>]

I'm having an interesting problem that I can't seem to fix.
I'm getting irregular spacing between section titles and the first
paragraph.
This ONLY occurs when the section has a subsection.
Now my book has chapters and each first section has at least one subsection.
Thus, all of my first level sections have this extra space between the title
and first paragraph.
My second level sections do or don't depending up whether they have a
subsection.

Is there a way to control this?

Paul