Wow...I have 18 with no holes at all. Not even a hint of chewing.
I can take some pics of the rack with the bus tubs that have been in use for over a year now, if anyone would like to see them.
Sounds like you need to cull the chewers. They learn from each other. Also make sure food and water are always available. Hunger or thirst could drive them to seek a way out.
IDK.. something just don't sound right there.![]()