Zoom does not slide smoothly between stops

Eente501

When I use the zoom it gets heavier after 24mm and 35mm, and I have to push to reach the 45mm. Sliding back to 24mm and 18mm goes easier but still I can feel "dents". I feel there is some mechanical problem. Other than that the lens is working fine. It seems to be the piece that has to do with moving the zoom back and forth.