There are a number of things that can contribute to need to use excessive force to cycle a Star, and they can all be additive. The first thing to do is to check for any binding when the machine has no rounds in it. You should only be able to feel the force of the spring until you get to the last bit of travel when you will also feel the force of the primer punch spring. If you feel any binding, you need to find out where it is and fix it. Common areas are the dowel pin, and the primer mechanism.
After you are sure that there is no binding with no ammo in the machine, then checking each station by itself.
Also, if you are using new brass, it can be a lot harder to size the first time. I find new Star Line brass very hard to size the first time, but after the first time, no problem.