[Bama_SIM_Cam]

Same here, except mine starts at about 5k which is why I haven't noticed it before (been babying her this summer I guess ;-). From what I've read, I think one likely culprit is the metal-to-metal contact in the cue ball mount. I am going to take it off and put some Teflon tape over the threads too and see if that improves it. How much did you put on, one layer? More than one?

But first I am going to "experiment" a little more (at >5k) to see if I want to fix it or not. Another indicator of approaching redline isn't necessarily a bad thing:-). But if mine was starting like yours above 3k I would try to fix it now but I don't have any ideas other than the tape.

The next place to try some tape is on the actual shaft. Did you add it there too? I am going to see if I have enough Teflon tape on hand first.

I am interested in what others have observed and done about this too. Just to be clear, it is not a general noise issue. Mine is perfectly quiet until I hit around 5k then a I get a very loud metal-to-metal buzz/chatter neither of which quite do the sound justice. It sounds like a circular saw cutting a nail and it has no perceptible build up, it just starts once the RPM hits its "release me now" limit which for my setup is about 5K.