The finish on the gears leave a lot to be desired. You can gently grind/sand the teeth then polish them. All you want to do is smooth them out. It's just that they're so rough they are lapping themselves in as you ride. Gear sets for cars are run in before they are installed. Proper preperation extends the life of the parts.
I'm getting a new motor this summer to work on. One of the thing on the list of upgrades is polishing the gears then applying Techline Powerkote Dry Film Lubricant to the teeth.
Oh, those dampener pads are an elastomer plastic that is intended as a sound dampener. I have installed them. You can tell it will work when you tap on the part it doesn't sound metallic anymore, it just sounds dead