Found the missing ball and bought a couple more.
You might want to go back and get all new ball bearings. That is a lot easier and cheaper the replacing cups and cones. Though I am sure lots of people do so, using mismatched ball bearings is not a good idea! If the bearing(s) you added are just a touch bigger, they will carry an inappropriate proportion of the load, wearing very quickly and/or or snapping in half.
Anyway, just an opinion.