z2

http://blueballfixed.ytmnd.com

There's at least one spot where balls look like they're being destroyed, and I'm trying to figure out where they're replaced.

trying to figure out where they're replaced

I did that once -- I don't remember where it started and ended though.

I finally found a goof in the animation: The envelope vanishes into the whitespace after it delivers a ball.

Goons made it.