global name 'self' is not defined

[Evan]

In answer to the 2 replies, I had no references anywhere to 'self'.  In
order to post my code I rewrote 2 scripts containing just the relevant
parts of the problem; these work.  However, they are identical to my
original code.  So I have deleted the 'old' script2 and renamed the new
one, and no problem.  I don't know why it worked with one and not the
other when they are identical, but I have what I want now.

Thanks for your replies.

-Evan