I was also having power button problems - more similar to those described by @LBF24 in this thread (but that thread’s been closed so I’m commenting here). In short: the power button started requiring more and more pressure to operate it, until it got to the point where I was afraid of damaging it. So I thought I’d better have a look inside.
Here’s how I fixed it, hope it’s useful to someone:
I followed the teardown instructions (PLEASE if anyone follows that: remove the screws before prying anything; the teardown incredibly misses this step! The ‘display replace’ instructions are better, and there’s a video of a guy successfully following them on YouTube which I can’t link to because apparently I’m only allowed two links in my post… OK you know best!)
The motherboard was really covered in dust and fluff - I think this was the cause of the problem. I examined the microswitch with a hand lens and there was no damage to it, it was still very securely mounted with no wobble or damage to the soldered pads. So I dusted it with a brush and carefully sprayed the microswitch with switch cleaner (being careful to shield the rest of the board) and reassembled it. It was better but not perfect, so I repeated it, and really flooded the switch with cleaner. And now it’s pretty much fine!
Took a bit of nerve, but like it says, it’s my phone (and I’ll pry if I want to).