PowerMac G4 MDD won't turn on after clean shutdown.

I have a mid 2002 1.25GHz PowerMac G4 MDD which works perfectly, except for one thing. If I cleanly shut down the G4 in Mac OS, I can't turn it back on without physically cycling the power to it (as in, unplug it and plug it back in). It's had this issue since the day I got it (I bought it used about a year and a half ago). This doesn't occur if I force shutdown the computer by holding down the power button, however. I've tried resetting the PRAM and the PMU; neither helped. Any ideas as to what could be causing this, and how to fix it?
For what it's worth, it still has the original power supply, although I did swap the fans for some Noctuas. All the caps on the motherboard look fine (I checked them today), and if I remember correctly all the caps in the power supply looked fine when I was doing the swap, although it has been over a year since then.
Thanks for your time, and please be kind. This is my first time posting on 68kmla.
 
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I would recap the PSU as a matter of course. They are extremely unreliable in this model.
I've heard that (quite possibly from messages you've left in other threads lol). I'd rather not if I can help it since I have very little experience soldering, and am a little nervous to crack open the power supply (again). Besides, I don't even know what caps I would need.
Is there any way I can tell if the PSU is the issue before I go recap it? If not, can you give/link me a list of the caps I will need so I can at least come prepared? And also, do you have any advice to help me avoid, say, shocking myself or ripping off the pads? I really don't want to ruin my PowerMac 😅.
 
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