Ladies.....It is not a default of your machines, it's the way the cartridges are designed. The cartridges are designed for them to not cut symmetrical.
I have had both my Cricut and Expression for several years now and even teach the machines. There is nothing wrong with the machines. The cartridges are designed that way.
Perhaps some of the newer cartridges are not that way. I'm talking about the older cartridges like Doodle Charms for instance.
I haven't purchased any new cartridges in about a year. I find the new ones now have many of the same images on them as many of the older ones.
I love the 100+ cartridges I have and they serve my needs for images.