Will say I did some more work this afternoon digging out the old caulking and it appears the contractor used a crack chaser bit to create a "v" groove just deep enough for some of the caulking to sit in. Bunch of clowns.
I would try to start in a inconspicuous place if there is one, those curves will be difficult and the blade will want to cut into the stone vs the concrete. You can see in some of the pics the deck is already moving independently from the coping. I would think you might just need to get a better joint that will hold the sealant to give you a more uniform joint.
I am actually kind of relying on the stone cutting easier. I am thinking that will help me create that separation. I am going to try a couple of tool options to see which gives easier and best results. Oscillating tool with diamond grit grout removal tool.....and if that doesn't do it, then step it up to the Rotozip with a diamond or carbide tool.
Those cracks are just movement cracks. If the deck was pushing the coping it would pop it forward. The once crack by handrail is a settlement crack from poor backfill compaction. We always set coping first. That's proper sequence of events. The trick is knowing how wide the coping will be and pouring the slab for it slightly smaller so theres full depth base behind it for deck. Before deck pour we use 1/4" spacer and pour up to that. That breaks down amd then sealant is applied over it. You dint want water draining thru anything om a pool deck you want it running away from pool to edge or drains. Only a diamond wheel will cut thru that to make a new joint. I would either open up amd re point the stone or seal them as water getting in will make it worst