valvestop

I have this pull to close valve. When I tried to pull it, it seems stuck. I am afraid to use too much force. If I use too much force, I will pull the whole thing out of the wall and create a big mess?

I just finished tiling the shower and was ready to turn on the water and finish the trim installation and the left (hot water) side of the valve stop broke off while I was loosening it with a flat head. I can't get a anything in there to unscrew the bolt (which I already sort of mangled as you...