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I have the first version of the Canon EF 24-105mm F/4L IS USM lens. It has annoying zoom creep. If I walk around with this lens, with the camera hanging from my neck, occasionally the zoom automatically extends from 24mm. This happens rarely enough that checking the zoom ring every 5-10 minutes is enough to stay most of the time at 24mm, when walking around -- I counted approximately three occurrences of zoom creep per hour when walking around. There is no zoom lock in this lens. I have never found the zoom ring too hard to rotate, contrary to the criticism by Ken Rockwell.
I would like the zoom mechanism to be stiffer so that the zoom doesn't creep. How to achieve this? I wouldn't want to throw away a perfectly fine second-hand-purchase and purchase a 1200 USD new lens instead. The lens is absolutely flawless apart from this zoom creep issue.
Related, although this question asks about the typicality of the issue and not how to fix it: Is it typical to experience zoom creep with the Canon EF 24-105mm F/4 L IS USM?