Some of Logitech's mice with the very useful Hyper-Fast scroll wheel have balance (or axle location) issues. From my research this seems to be common. As you can see this is a HARDWARE issue, which Logitech seems to have trouble acknowledging on their support forums.
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IF YOU HAVE THIS ISSUE: Keep all the packaging, it's not always bad enough that you notice right away. I had used some of these mice for a week before noticing the issue, it didn't happen every time. Gently spin the scroll wheel many times like in the video, and look closely. Exchange the mouse with the retailer you bought it from for a replacement, it seems to be a matter of trial-and-error to get a working model.

0:00 MX Master live demonstration
0:05 MX Master closeup
0:19 MX Master closeup (slowed down)
0:47 M705 Marathon closeup
0:53 M705 Marathon closeup (slowed down)
1:06 M500 closeup
1:15 M500 closeup (slowed down)

My Logitech M500 (last in the video) works perfectly and has for 5 years. I also never had an issue with my M560 (not in video).

However my M705, and recently purchased MX Master have this common issue, and the $100 MX Master is the worst of all, sadly. Also, since making this video, I've bought a G502 from BestBuy and returned it for the same issue. I didn't exchange it because I was worried that I might have to do so more than once to get a good one (which wouldn't be terrible if I bought it in the store, but I bought it from BestBuy's eBay account, where returns and exchanges can take a very long time).


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