Shuttle PC wont power up

I have a shuttle system I built for someone else that is having strange issues.

It started about 6 months ago. When you try to switch the system on, nothing happens, but about 30 seconds later it suddenly starts booting up. This has now extended and you can press the power button, go away, make a coffee, make a phone call, and come back to it 5 mins later as it’s just powering up.

Anyone else come across this?

Scream

After scouring the web, it appears this may be down to leaking capacitors within the power supply. Will have to order a new power supply and check it

Forgot about this and just remembered now - I had the same issue with my SN45G if mains power was removed completely and it was indeed the PSU.