On the flat, if a horse enters the stalls, the gate closes behind him and the main handler raises his arm to say ready, any horse that does not start should be declared a runner. The only exception should be a horse(s) playing up resulting in the jockey not being mounted or in the "ready" position. For example if a horse is rearing badly the call for a start should not be made. If un-readiness ( is that a word

As for loading a horse, there should be 3 attempts allowed to load. After attempt 2 if the horse looks recalcitrant the starter or his assistant should issue a warning that last chance is imminent. An orange indicator could be attached to the runner. If the horse fails to load on the 3rd attempt a red blanket/cover/ribbon should be attached to the horse to indicate he is now a non runner.
This may seem harsh but really it is quite simple. The trainer should be made to perform stalls testing more often to the point where the horse is used to the stalls and not overly upset by them. I appreciate the full stress cannot be created in tests and practice but it is clear that this is not being done by trainers. Some argue that they need to get the horses fit and fast but what is the point of that if the horse then plays up, won't load and then ends up as a non-runner. We all know that some horses end up having to pass a stalls test should they fail to load or be problematic or be reported by a starter so this is nothing new. It just needs more attention to detail from the trainers and these problems would be reduced.
I know some will say that horses are not machines and I am fully aware of that. However, a horse causes problems because it is nervous, anxious about the surroundings at the start. They are unfamiliar and unnatural so some are bound to become upset. The more they practice and become familiar the less likely they are to cause issues.
On the jumps there are no stalls so it is a case of the horses circling in a a collection area. The starter or assistant should then notify jockeys that they have 30 seconds or 1 minute (they can consult to agree) before they are asked to enter the pre-race start area. This area could be 100 yards from the actual start line. When the instruction from the starter is given to file out all horses should make their way to the pre-start area and be given a preset time to perform this. If a horse refuses to leave the collection area it will be given a warning that it has 1 minute (can be consultation to agree time) to make it's way to the pre-start area. If it does not make it to this area within the allotted time then it is declared a non-runner. If it makes it to the pre-start area then it will be made ready and asked to move towards the start. If it then plays up again and does not move forward then it is declared a runner.
Again this may sound a bit clinical but let's face it we currently have nothing to go on. The horse is on the track he's not on the track. He was under starter's orders, he wasn't under starter's orders. It's all a complete mess and there is no structure.
Some will argue it will all take too long with predetermined times in the collection and pre-start area but let's be honest, how many races start on time? Instead of the starters standing around having a chat they could be timing the proceedings and giving structure to things.
I am sure that once these rules are in place, trainers will know what is expected of them. They will have structure to work with and will have redress should their horse incorrectly be declared withdrawn or a non-runner. At the moment there is nothing and anything can be said to justify a decision.