I went through all this too when I first started reloading. After a few calls to Hornady everything was cleared up.
The biggest cause of the expander ball being hard to pull through is because the die is making the neck too small.
There are two causes of it making the neck too small.
#1. the brass in the case neck is too thick, most likely the problem since the die is squeezing the neck from the outside, thicker brass makes the hole too small and then the expander hangs up and is almost impossible to pull through, or
#2 the hole in die is too small, thereby compressing the neck too much. Hornady suggested I could send the dies back and they would open upthe hole for me.
A simple test for this is to turn the case necks down some and then try sizing the necks. They will pull through much easier when the brass is a reasonable thickness. This also explains the inconsistency of how hard it is to pull the expander through case to case, as I am sure you notice they are not all unbearably hard to pull through the die.
One other cause is really hard brass. A test for this is to anneal some of the cases and then try again. They will also pull through much easier when the brass is soft.
I have since gotten rid of all my regular dies and bought Redding Type S bushing dies. They solve the problem of brass in the neck being to thick as you can compensate for that with a different size bushing.
This does not completely solve all the problems though. If your case necks are not all the same thickness you will still end up with inconsistent neck tension since the sizing occurs from the outside. There are two choices to solve this, either turn the necks of the cases a small amount to make them all reasonably the same thickness or leave the expander ball on the Redding Type S bushing die.
I too had this exact same problem when I first started reloading and found the Redding Type S bushing dies so much better than regular dies, that I will never buy a regular die again.
Once you size with no expand ball there is no going back, it is just so much easier.