I am dead set against taking a knife to the panel, cutting a slit, poking in a lump of flock which usually ends in a lumpy panel. Not good for the horse either. If I am called out to look at a saddle on a horse that is causing a problem, the problem is usually very obvious to my trained eye, and I would know what to do to remedy it immediately. I would then book the saddle in to be done in my workshop, where everything is at hand that I might need. The whole aim is for the panel to be a soft cushion between the tree and the horse, and it is impossible in my opinion to regulate in situ. It is nice to have horses ready for me when I visit stables. Obviously there are circumstances where it is impossible. I must add that most people have everything ready. But you do get the exception. For full dairy see West Sussex Gazette Aug 1