I was trying to replace the chick holders with the quail ones and I messed up. This is what happened....

I thought that the white knobbie thing (is that it's scientific name?) just slipped into the grove but it won't stay when it starts turning.
Will someone please post a pic of theirs so I can see how it is supposed to go. I can't tell from what little documentation and of course I didn't check it before I started trying to change it.
Thank you so much for any and all help
I thought that the white knobbie thing (is that it's scientific name?) just slipped into the grove but it won't stay when it starts turning.
Will someone please post a pic of theirs so I can see how it is supposed to go. I can't tell from what little documentation and of course I didn't check it before I started trying to change it.
Thank you so much for any and all help