Brian - you're welcome. Not to beat the subject to death, but if you can hear that you're off, and you've got the time to practice, then I think you are on the right track with side markers. They'll help you with the big jumps, but your eyes will never be as good as your ears for getting it perfect.
The second octave always takes a little longer, but every once in a while (when you're really into the music, rather than the technique) you'll find that you're nailing it. And over time, that will happen more often.
Enjoy.