REK-O-KUT LOW NOISE SWITCH RATTLE
The "problem" is identified as a rattle coming from inside the switch's case when it is shaken.
Do not be alarmed. The case is fastened together with what are called "pop" rivets. Occasionally, this can leave a tiny portion of the rivet insertion material inside the case. It cannot get into any component to cause any failure whatsoever, and is considered a normal product of the manufacturing process. . The only time the rattle can be identified is when the product is shaken.