Unable to print

Have been trying to fix the extruder issue I have. Seems like this extruder-bowden-hotend chain of problem is quite common in many cases. Could be originating from a flawed design but since there are so many parts involved in this with various factors such as temperature, random filament diameter(from 2.85mm to 3.1mm), thumbscrew pressure(completely analogic, no ways to measure force), extrusion speed, etc.. My problem seems to be a combination of a few, which makes it more difficult to even figure out where to start. Hoping to solve the problem this week.