I had alot of failed prints so late last year I did some redesigning of the printer. The weight of the stepper motor on the gantry was causing acceleration problems and was causing the hot end to bounce around . This was causing the prints to have blobs and eventually would fail the print.
I decided to move the extruder off of the gantry and use the Bowden design. This made a big difference in the prints and now I have been able hit print and walk away without the concern that I will come back to a big blob of plastic on the hot end.