Remaining days..

• Day 10 part 2 (pipe path, winding path)
• Day 12 part 2 (unfolding "#.?" patterns...)
• Day 13 part 2 (smudge on the lens, reflecting lines)

Ahh another solution for 13.2 would be... test for every reflection line, how many things are WRONG. If only one, that's your new reflection line.