If your right and left pedal are a matched pair then they both should have 13 balls at each end. The reason for the loud click is the shortage of balls, some of which have probably disintegrated with use (or been lost during a previous rebuild).
Leave the lithium grease where you found it, head off to your local auto or hardware store and get a tub of general purpose grease. People here can talk for weeks about grease, but nothing on a bike except a coaster brake hub is really under that heavy a load. It just has to stay in place.