May I suggest to take the pictures of the disassembled switch before and after cleaning the grease, especially the areas that have scuff marks. It will be more helpful for the members to give better suggestions.
The area that is sticking could be the centre part of the rotating knob.
It could be the bent spring, if it is using springs and metal balls.
Or it could be worn out detent spring which is made out of plastic.
The reason was a sticky substance under the red switch. Really a very little amount of it. Alcohol was unable to dissolve it, but water did, so I assume maybe it was some kind of sugar... or something other.
I also cleaned a grease I applied earlier, where springs with balls go (maybe it is not needed as it was dry before my intervention).
Now switch turns as new, with clear steps, just tra-ta-ta-ta
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/grin.gif)