I bought an Ender 3 two days ago and assembled it today. I think I did it properly, tested the movement of all axes which works for ever axes. Then I performed the calibration as described in the manual. Used piece of paper and adjusted the bed until barly fits underneath the nozzle for all four corners. Afterwards I wanted to print my first model so I selected the cat from the usb stick which came with printer. And now comes my problem. I let the printer run for 15 minutes. It moved and moved and moved but there was no filament on the bed. The nozzle and bed were heated properly. The one thing which I noticed was that the stepper which feeds the filament turns for like 30° and then flips back: to me it looks like the filament can not be fed in. After canceling the print the extruder moves back to the home position which is like 5 mm off the bed and then suddenly the filament flows out of the nozzle.
What part of the configuration I'm missing?