I do not know if  sticking is the right way to explain this but I play a game (Rocket League) and the scroll wheel button is used as your reverse look (default use). The button does not actually stick as you can feel and hear it ‘click’ but the action of the reverse look will stay reversed which it should not. It is like a ‘quick view’ of your reverse angle of you car and only stays this way if the button is held down, once you release the button it is suppose to return to forward look. Now this does not happen all the time but it does happen on its own sometimes when using other mouse buttons as if there is something causing the other buttons to ‘graze’ against the mouse wheel button that may be causing it to depress inadvertently. I do not want to take the mouse apart before finding out if this may be a defective part and a replacement mouse is the best result. The only thing I can think that would cause this, other than a defective or worn part, is maybe something is on the button itself that would cause it to ‘stick’ not allowing the button to be fully undepressed and go back to the fully undepressed state. I realize there is probably a spring that pushes the button back to the original state but if the but if the button has a foreign ‘sticky substance’ on or in it, that may cause the button to not fully retract, maybe. In that case, since I cannot see the button without taking the mouse apart, can you suggest a way to clean it without taking it apart? 

I have used this mouse without this problem for at least 3 ½ years and I do not use the mouse wheel button anywhere close to the other buttons on the mouse. So, I do not think this is a ‘wear and tear’ issue as I do not use this button very much in the game or any other type of regular use. That game is about the only time I use that button. I do not see this as a problem with normal use outside the game like scrolling through web pages and such.