Z-Axis Troubles

I've been running my C-beam machine for a little while. I have gotten a few good runs in. There has been some serious learning along the way!!

I am having a problem with my Z-axis that I cannot figure out.

I have been trying to machine an aluminum fixture that is basically a .5" dia hole .75" depth with an 1/8" slot cut in the side ( making a clamping fixture to hold a .5" piece of round bar.) Anyway, when I run the job it never cuts the whole .75" depth. (I am taking .010" cuts). Then...

Z-Axis Troubles