Training the older horse to stop

Older horses sometimes have a hole in their foundation. I have a 17 yo mare that doesn't have a good stop. She will transition down with seat cues and breathing, but the transition from a walk to a stop is terrible. Tonight my husband rode her and I taught him how to work on her stop. He would shorten his reins to be prepared to use them, then stop seat movement,  exhale, sit down and back and if no response slowly pick up the reins and apply pressure. The release was when she gave to the bit, not when she stopped her feet. Why? If she stops her feet, but is still pulling her head forward and against his hands, she is not mentally stopped. She needs to stop 100%. At first she thought he wanted her to go backwards. Again, he waited for her to stop her feet and then give to the bit. He was consistent, so she started to understand exactly what he was asking.

If this doesnt work and the horse is so strong that they blow through your hands, another way is to laterally flex the horse into a stop, and then back up in your training and just teach them to give to head pressure from the ground, using a halter, then switch to a bridle. Takes time but even an older horse can be retrained to have a good stop.