The current mechanical Rotary mechanism is different from the older Rotary mechanism. The older one had 7 tiny fingers and the current one has 3 much more robust fingers. Some of the lights will make the noise, and some won't. It all depends on how those fingers are going over the contact board. It won't effect the light. Some that start smooth will end up with the noise, and some with noise will go silent. It's normal. Not great, but yes, it is normal. The next iteration of the Rotary tail is going to address this issue even though it doesn't effect reliability... in fact, it is more reliable than the first Rotary tail that was quite smooth... but the noise is annoying, and Henry doesn't like it either.