M Vincent -

... I have very erratic success when I copy a figure from Excel and paste
into Word or PowerPoint ... <

Have you tried some of the Shift Edit | Copy Picture options?

If you can get the embedded chart looking the way you want in Excel, select
the chart (click just inside its outer border), hold down Shift and from the
Edit menu choose Copy Picture. Try various options. Then paste into Word or
PowerPoint.

- Mike
www.mikemiddleton.com