I also find it "hit and miss". I only did it a few times, and i remember very well that once or twice i got it right first time. But i could not remember where exacly and how i placed my hands to succeed. As far as i remember, it was was easy enough to make the cable end meet the angle drive, but i could not find easily the correct angle of the extension to start on the thread. Things got worse when the last time i put some extra insulation in there. The boroscope sounds an interesting idea to try.