Troubleshooting

What exactly do you mean, troubleshooting?
Here is what I mean: no horse is perfect. They either have temperament faults, conformation faults, or bad habits.
Explained in this article are a few of the temperament faults and all of the recognized bad habits. Conformation faults are explained in "conformation."
Two of the most common temperament faults are:

Disrespect, therefore a bad attitude
Fear and shyness

Disrespect comes from a horse that thinks he or she is King or Queen of the Hilltop, or at least king of his domain. They will not do as you say without using a whip or some other harsh method. These horses must be taught respect.
Fear and shyness comes from a horse that knows you are a predator, and therefore absolutely fears you. This horse will likely be hard to catch. They do as asked, but always with a quick motion, and always with fear in their eyes. You must win their confidence.

The recognized bad habits are:

Cribbing
Chewing
Weaving
Stall Kicking

A horse may fall into any habit, such as tossing the head, dancing on their toes, etc., but these are the recognized habits.
Cribbing is when a horse takes hold of something, such as wood, and sucks air through its lungs. This is bad for a horse's health. A cribbing collar should be purchased, as all habits are tough to cure.
Chewing is undesirable. The horse will chew wood down, so that it must be replaced. This can result in splinters.
Weaving is when a horse places its head over something, such as a stall door or fence, and sways back and forth. This is not good on the horse's legs.
Stall kicking is when a horse kicks their stall, often kicking out the walls so that they must be replaced. This type of horse will need to be kept in a paddock or pasture.
All vices, or bad habits, come from boredom or frustration, or both. Keep your horse active by doing a lot with it, or keep it out in the pasture with other horses. You can keep your horse active in a stall by giving them hay in a hay net. The hay net makes it harder for the hay to be removed, therefore you will not make your horse fat. Even so, give them plenty of exercise if you do this. Some horses, especially young horses, like to play with a ball. You can purchase a ball to hang from the ceiling of your horse's stall.
Remember that there is no such thing as a perfect horse!!