A: Not exactly. The motion to use isn't to Amend Something Previously Adopted, but to Rescind. They're similar motions, but differ in that Rescind kills something previously adopted, while Amend Something Previously Adopted changes it without killing it. They're both described in the same section (34) of RONR.

There are lots of conditions and details, but for the specific situation you describe, here are some of the more important ones.

• You can't undo what's already been done. If you've already mailed out some of the ballots, you can't pretend it didn't happen; however, you can cause any unsent ballots not to be sent. Beware: this would be very confusing (some people getting ballots and some not) and potentially a political hot potato (no, there's no "e" at the end of potato, Mr. Quayle).
• At your meeting, someone would move "to rescind the motion adopted at the last meeting to re-mail the ballots." Another member must second the motion.
• Debate can be about the advisability of rescinding the vote, or about re-mailing the ballots.
• The affirmative vote required to rescind the motion is either:
  • Two-thirds of the votes;
  • A majority of the entire membership (present or not, voting or not); or
  • A majority of the votes, with the entire membership having been given previous notice of the intent to rescind the motion.