I have a nice little collage that might help you with the pied markers.
Only one of these animals is a known 100% het pied, though they all have belly markings that could be confused as pied markers. Can you guess which one is the het pied?
The het pied is the top right animal. All the others are completely normal. "Pied markers" can be a combination of a number of different things, including a connected neck and eye stripe, wonky tail pattern, a ringer, or train train tracks. A het pied can have all or none of these traits. Mine happens to have none of these except for an oddball tail pattern and train tracks.
When you are looking at the tracks, they "should" be very bold with very clear and concise defined lines between light and dark. They belly itself should also be very clear.
Here are a few more photos of het pied and possible het pied. I am on the fence on whether or not the possible het will prove out.
Pastel 100% proven het pied
Pastel 66% possible het pied
For a Yellowbelly you look for lots of nice flaming coming up the sides, many small speckles along the sides with a clear belly, a head stamp, and yellow outlining the markings.