The blob is the result of crashing from Z-axis into the print not from knocked of the print..I suspect that if it crash it also extrude a lot of plastic at the same time.I went to the G-code file and found sofar nothing strange.I saved the file from the internal micro sd card to my computer.I will copy that file to the external Sd card and run that file...see what happens.I think I have to inform Flashforge also.