May be a stupid question but Bottom Normal Contacts? It should have mechanical switches with contacts If it doesn't see them it will go through. If the rolled guides are in rough shape or too much slack the cam vein might miss the switch at full/slow down speeds where as on a learn run it is runinng 5-10 feet a minute and may be opening it as it should every time but not at learn speed. I would be willing to bet it has something to do with the normal.