I assume that no material comes out of the nozzle when you start a print, right? How about material loading - the material, or does the problem occur only during the print? Could you provide some videos that illustrate the issue? Does the motor sprocket wheel stutter or click? This would help us to find a root of the problem. Also, have a look at the troubleshooting manual.
Moreover, please note that despite cleaning the nozzle - the hotend might be clogged with material residues, or some other consumable part is worn-out. Have you replaced any parts recently?