Re: Case sensor
Once I did the same thing with a tower box, but it involved a fist bang on the top rather than a mallet.
The PSU fan was on its way out, and would get stuck when the machine was turned off for an extended period of time. So when someone turns off the PC and leaves it off overnight, in the morning the PSU fan won't spin up unless you give it some taps to get it started ( I guess the PSU would detect the fan not working, and cut out to prevent overheating/fire hazard).
The PSU was mounted at the top of the tower, so the lazy "fix" was to power on the box and thwack the top of the case and get the fan spinning, after which it would work until left off for a few hours.
Fun fact was you had to get the timing right as well. If you wait too long before the power on and thwack, the PSU would cut out before the fan started spinning. Likewise you power on and thwack too early, the fan hasn't been powered up and won't start spinning, and then it would cut out. So for those not in the know of what the problem was, it seemed like a magic touch. Hearing other people in the office thwacking the box before they would come and ask me to do it was quite funny.
It was a "low priority" fix, primarily because the desktop was scheduled to be replaced in the next hardware refresh, and the PSU replacement was a fiddly job, involving removal of the motherboard to get the PSU out.
This kind of fixing is quite common, so much so it even has its own term "Percussive maintenance", which I first heard on a (now old) comic:
http://ars.userfriendly.org/cartoons/?id=20010326
Biting the hand that feeds IT
