I had to crack open my C750 last night because the external power button had broken.
Inside, the switch was in good condition but the power button had broken. It seems that the power button is part of a larger piece of plastic that goes deeper inside the hinge. The button must be in the correct orientation in order to push on the switch. The larger piece joins the smaller piece by the tiniest thread of plastic, probably less than 2 mm in diameter so it is no surprise that it eventually broke.
I have tried to glue the tiny part of the button that is supposed to push against the switch to the actual switch itself. It was very difficult to get a small enough blob of glue on the right place. I'm not expecting this to be a robust solution.
I'm thinking that the only way to solve this is to try to make a very small guide to glue in position. Has anyone made a nice power switch mod or solved this problem in a neat way ?
(P.S. I can use the Home button for power on and Suspend from the menu for power off as long as my Z has booted)