How to fix a loose and broken stone on a set of front steps

This bluestone staircase has seen better days. The mortar holding down the center square stone has failed over the years and the mortar has turned to sand. The stone is now a safety hazard. It shifts under your feet and can tip up if you step on the edge. There is the stone to the right also a major safety hazard. It is cracked and missing a large portion of it directly where you would step going up or down the steps. This happens over time from wear and use and the powerful “Mother Nature”. If you catch the repairs while they are small, and DIY homeowner can fix it. I use a Dewalt grinder with a diamond blade and grinding disk. I also added some bonding advent to the mortar mix as an extra insurance step.