Luggage Repair.  Zipper Pull Replacement Instructions.

The Zipper slider has a small flange on the top. If the missing or broken zipper pull became snagged and came off, there maybe enough room to slip the new zipper pull, into the existing opening. Just gently squezze the flang down on the slider, after inserting the new Pull.
If the new pull does not easily slip into the existing opening between the flange and the top side of the slider, "Gently", pry the flange up,
(I use a small screwdriver), just enough to insert the ring end of the new pull, and squeeze or press it back using a pair of pliers. Be gentle, so as not to crush the teeth of the zipper in the slider itself.
   "Caution"   if you have to pry the flange up, Do so very gently, and just enough to slip the new pull in. To much pressure may break off, a weak flange.