Printrbot Simple 2014 Z axis stabilization

I created this part because I was getting banding. On surfaces that should be flat I was getting a wavy effect... I didnt think that its the resolution because I can tell that there are multiple layers between each peak and valley. I come to find out this is cause because of Z axis wobble.. I have seen the Z screw wobble but, didnt think it was a problem. I already saw an improvement using a 3 layer test print when printing this part. Hopefully the next couple prints with the full size part