Removing the xclamp and replacing the leg bolts with washers and bolts is a horrible idea.
A proper reflow with insat super flux and a good reflow station,not a heatgun will ensure a better quality repair.
Albeit,a reball is the only permanent fix.
Dont be suckered into buying xclamp rrod repair kits.
They are garbage.
Reflow with the proper flux,repaste the gpu and and put the xclamps back on.
Retention can be established by placing steel washers on the side close to the motherboard before reattaching the x clamps.