Use the STL for the nozzle size you have installed or use the openSCAD file to make your own custom file. I always have these gCode files on my SD cards, anytime I want to check the level of my bed I just print the corresponding file and adjust the screws as needed to get the perfect plastic. it will print the zig zag pattern front to back 2 times so.... 1. Start with the front two thumb screws and make sure you're getting a FLAT topped line of plastic that is not too thin and sticking to the bed. 2. As it works it's way back check the back. 3. If the bed is close, I just cancel the print after the 1st pass going to the back. If the bed needed a lot of adjusting, then I let the print come back to the front and remove all the plastic before it works it's way to the back again.