Hi Kevin,

It's UCAC2_PATH, not UCAC2_DATA.

Full details are at

http://www.projectpluto.com/update8c.htm#ucac2_display

"...once I zoomed in to level 9 or above, they finally started
showing up."

You can right-click on any UCAC-2 star, then on "Display",
and it'll tell you at what levels UCAC-2 stars are shown. (Similarly
for most other datasets in Guide. If Guide had one of those "tip of
the day" features, the first tip it would probably show you is:
"If you see something on-screen and want to know what it is, or
want to change its color or turn it off or adjust its limiting
magnitude or the levels at which it's shown, right-click on that
object, and then on Display.")

"...One other thing... is the data file you modified named
GUIDE.DAT or GUIDE8.DAT? I modified GUIDE.DAT (no 8 on
filename)."

Should be plain ol' Guide.dat, no 8.

-- Bill