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 will show even more improvement. If you try it please let me know how it works. Note: I did sand down the hole for the z axis screw a bit so I could put one layer of painters tape around the threads (just so it wouldn't screw off)..