The methodology is: Play It Again, and Again, and Again, et seq. The bits that seemed difficult get just a tiny bit easier each time. Now it's moving to a new stage, which (I think) means it's moving into the process memory, where it seems to be acquiring plasticity as to tempo, note length, velocity and feel. To put it another way, when you stop having to think about what note's coming next, you're free to work on it as music.
It's nearly there, meaning nearly in a state to record it for YouTube. Another three or four hours? Which, means all over a little more than 30 hours altogether. In other words, one hour per bar. Which is worth noting for future reference.