Re: My first build.
That knocking sound is probably rattle from the right side engine cover, or gear tooth lash from the gears underneath that cover.
Take the cover off, and dab a pea-sized drop of grease in between the large ring gear and the small bevel gear.
Inspect the inside of the cover you removed; if there are scrape marks on it, you may need to gently grind some of the inside of the cover, so the clutch pins don't scrape it. Or add a second gasket to it to make it stick out farther.
To stop the cover vibrating, you need to stick something to it. Cut and glue a piece of mousepad to the outside. Someone else recently suggested spraying some disc brake quiet on the inside (I really like that idea).
Those two things should quiet it down a lot, and don't forget that these motors are just kind of rattly by their nature. It's not a Rolls Royce.