There is an article in A to B magazine. Look up "Brompton mystey rattle solved" or something like that basically he tin can metal thing that covers the extra set of pawls on the driver rattles get it tight ebough so it can rotate without binding. My personal experience though; Pinions rattle agains the ball ring/planet cage. Especially in the AM hub they are quite meaty. Hence it does not rattle in gear 1 and 3 (ie when pinions are in drive) when pedalling but does rattle when coasting. 2nd gear rattles all the time. Solution in my case: liquid (NLGI 0 grade) grease. Apply liberally and it does quiet things for some time. After a while it does start to be noisy again. I guess once it spreads around from all the spinning parts. I am still trying to figure out how much and where to put the grease but overall that seems to be on the right track.

-Carcinogent