The following method has worked for me. Put a small drop of ca glue on a piece wax paper or tin foil. Use a small piece(1" to 1 1/2" long) of small diameter music wire, .015 or so and dip the end of the wire in the drop of glue and then then touch the end of the wire to the dinged area. You will have to move fast so you don't stick the wire to the bow. You may need to try different wire diameters depending on the size of the ding. It also helps to put a 90 degree bend in the end of the wire where you hold it.
I have also also bent the wire double so it would hold more glue for bigger dings.
Always, try it on a scrap piece of wood first to make sure you have the amount of glue you want.
You can get music wire, (sometimes called piano wire I think), at hobby shops. It comes in many different sizes. The glue will build up on the end of the wire. Just scrap it off with razor blade or hobby knife. Jim