The one thing about these can toppers is they are not all made exactly the same.
The standards for making them appear to not be very high.
So..some fit tight, some not so much.
You will need to probably discard a few, that just don't work reliably.
The gates on your machine have got to be in good shape, move freely and easily.
I have had some come off the cans, trying to pull them through the gates.
Make sure they are on good and tight. If needed use a rubber mallet to seat them on the can.