Yep, in the 6 years I ran my Atlas, I went from 10 change gears to 20... and I only remember paying for two. They're cheap as chips, and apparently multiply like tribbles.
Translation: You don't need to worry about finding Atlas parts. Be glad you didn't buy something truly rare! The change-gear version of my current lathe uses four gears at $900/each, *if* you can find 'em. Glad I didn't need those!