What are final steps to evaluate click wheel center button?

Does anyone have the final steps as far as knowing when you need to replace the click wheel button versus the logic board? I have not seen any pics like all the others showing the "bumpers" that are supposed to be in place between the logic board switches and the center button. Also is there a pic showing the notches on the button new vs worn? Like others, my center select button does not work. the existing repair shows all steps to replace all other components, then stops short of detailing the button and switches on the logic board!

I would also like to know if it is possible to go from removal of the back case cover and first ribbon to the removal of the screws in the front cover to access the click wheel and lohic board contacts? Please help!! Thanks, DrJanMW