Thank you for all the helpful replies. It's so nice to have a community like this at hand.

I know there is a good possibility that my table does have more resistance in spots than others. This wasn't exactly a product of precision. I was hoping to get this thing working well enough to start cutting the parts for a better machine.

As far as the resonance goes, is there anything I can do if my motors don't have a shaft extending from the opposite side? I can probably see if 1/8th stepping will help any. I was just reluctant to do that since the Probotix driver manual says not to use more than 2.5A in anything but full step mode and my motors are rated for 2.8. My initial suspicions were that the motors lacked the strength, so I was trying to give them all the power I could.

Oh, and my leadscrews are 1/2"-10 5 Start ACME rod.