Took a ride today and heard a metallic rattle coming from the front end. When I got home I noticed that one of the axle covers was loose. Upon inspection I noticed there were two holes on each cover and only one hole had a set screw installed. I removed both covers. The set screw were extremely difficult to back-off. They had some kind of staking compound (like loctite) but it was sort of an off white color. Could be loctite 565 but not sure what it is. I looked at the online microfiche for the 2016 street bob but, the axle cover isn't listed. I ended up going to a hardware store and getting some stainless set screws. I put blue loctite on them (it's all I had) and tightened them (all four) down with an Allen wrench.

 

Not positive about the 2016 model, but axle covers are accessories which is why you won't find them on the fiche. You figured it out anyway.