"Most problems" you say? Yes, the laptop keyboard on this one Mac which was augmented by one or two drops of water. Fifty six screws the size of poppy seeds just holding the keyboard in. Had to remove the entire motherboard, unplug a dozen edge connectors of five or size different types.
I had to do this three times: first time to attempt to dry it out (90 minutes to disassemble with the right tools and space to do the job), second time when the replacement came but it was the wrong one, third time when the proper one came (90 minutes total last time around).
It's an awful design. The first thing you want to do if you spill water on a keyboard is remove it and dry it out. But it takes 90 damned minutes to do it, by which time the electrolytes have been dumped and the contact areas damaged. The keyboard assembly also includes the power switch, so there was no way to just unplug it and use an external one. This particular model of Mac laptop also has no power jumper on the motherboard. I was this close to wiring up a switch on the edge connector. When an external keyboard is plugged in, OS X doesn't disable the internal keyboard, either, so when your Control key is acting up and believes itself to be pushed in permanently, good luck! Unplug/plug/unplug/plug/unplug/plug the USB jack and after a few goes, it'll pick up the change. Also, for whatever reason, unloading the keyboard driver kernel extension did not work. Mac forum people aren't exactly the most diligent (or another word ending in "-ligent") of troubleshooters, so there were too few clues to go on.
I've had failures with floppy drives, hard drives, PSUs, monitors, fans, the 1530 motor controller on a Commodore 64 several times over because some thick lout at the computing club kept borrowing my tape deck even after being told. But this Mac laptop keyboard definitely presented me with "the most problems" in terms of irking me to the point of lining up a Windows machine for my next laptop, not this cheap shitty Chinese Apple shit.