Geeetech

I recently got an acrylic Geeetech i3 pro b, i built it using the instructions and YouTube tutorials, and for the most part it works, however the z-axis constantly provides trouble. I manually adjust the z-axis so that its perfectly level, i use a spirit level to check and i measure the distance ...

I'm new to 3D printing. I got a Geeetech A10 and set it up, hopefully correctly. Each time I print the test print (supposedly a dog), the print head scrapes off the first layer as it moves around. I've done the paper test, and I thought it was correct but maybe not. Any ideas how to fix this?