unwanted cellspacing in Word tables

Using Robohelp 10 on win 7 pc

I am having the strangest table problem when i publish to docx from robohelp project.

All the tables in word doc have 2px of cellspacing which makes them look like cubbyhole shelving (not what i want).

I hope someone in the forum will take up the challenge to help me out.

Here's what i know:

1. using the same style sheet (.css) and word template (.dot) files that i have used in many projects that do not have this problem.
2. started a new RH project and imported a framemaker project.
3. Used the RH "clear formatting" option for each topic to remove framemaker conversion garbage formatting.
4. Used the RH "clear formatting" option for each table to remove garbage table formatting
5. Checked the html of each table to make sure it was cleanly tagged table
6. Selected each table and used "table style" (and checked the clean up box) to add my own table css style (AM1) to each table
7. table heading looks like this: <table class="AM1" cellspacing="0">
8. In the print documentation wizard, i select the word template and assigned the "AM1" to the desired word template table style

After i publish to word and open the doc, all the tables have cubbyhole shelving look. By selecting the table and choosing "table properties" i see that something has set the cellspacing to "2px"

With my cursor in the table, when i view the table "design" toolbar, i see that the correct table style is highlighted. Now, if i click the table style to reapply it, cellspacing goes away (sets to "0") and the table looks correct.

What could be causing this cellspacing problem when i publish to word from this project? there must be a problem in my robohelp project.