I was just about to turn my 500 off but nothing happened when pushing the button. It stays on. The button looks like it is in it’s out position and you don’t feel the resistance when pressing it.
Exercising it is said to work but nothing happens and it feels lose. Ideas, proposals?
Ouch… Looks pretty simple though. Thing is it went from feeling ok to just being lose with no resistance. If the brass spring is being compressed I’m thinking it should feel strange until it’s not working but I’m no button expert 
Might be a project for the weekend then…
If I understand it correct that user solved it by pulling the brass spring apart a bit with a knife.
Have you got dealer near you?
Distributor and reseller around 3h drive from me.
See how you get on with the DIY job then. Good luck with it. Look forward to seeing if you solve it in same manner as previous thread I sent.
Yes! Went back now some minutes later and felt there was some resistance to it again. I then did the “push it in firmly then remove the finger fast so it springs out fast” and now it works as normal again
Fantastic news. Maybe take the plug off. And push it in and out a few times. Or leave it alone!
Is this the trick? In slowly - out fast ?
That’s the trick I read others suggesting. As far in as possible and then slide the finger to the side so the button “jumps” out fast.
But despite all the techniques, mine eventually gave up the ghost……just after a thunderstorm. My dealer fitted the rong feng as supplied by Naim….for free.
It’s good to hear that it worked out although they replaced it with the rong feng.
My dealer sent me a picture and a description of how to fix it remotely. Years ago and my memory lacks specificity. Unplug it, turn it over, loosen the cover, stretch the spring with a table knife and put it back together. I do not find any of the instructions or the picture now. And it makes a difference which screw you loosen to free the cover. I am not much help to you, but this issue is not uncommon and is easy to fix. Your dealer should know.
It’s your instructions in the post further up reposted by Dan 
Yours came back without opening the case - correct?
I see - the brass spring must got stuck.
Good, that it came back by itself - maybe it flipped over by the remaining spring travel.
Yes, no need to open it this time around 
Strange that these buttons are so fragile - there is not much on/off to do at naim and a mechanical button is no rocket science.
Are all buttons the same on all black boxes?
Or is it an exclusive 500ps problem?
In my personal experience with my 500 psu, i talked to my dealer and tried all the soft/hard press stuff…….then it worked again. Rang my dealer……great no need to come out and fix immediately. They said it will happen again so we will get a new switch. Took the psu in, it takes 10 minutes or so……f.o.c…….no problems since.
