We just bought a house where an old man lived for 27years. When he built the place, I doubt that he had any idea that the voids in the brick were weeping holes. I would like to fix them, but I'm not sure the best way to do it without hurting the bricks.
Use a Plugging Chisel.
A plugging chisel has a tapered edge for cleaning out hardened mortar. The chisel is held with one hand and struck with a hammer. The direction of the taper in the blade determines if the chisel cuts deep or runs shallow along the joint.