IIcx/ci/Quadra 650/PM7100 power supply disassembly procedure ?

[Renegade]

Hi,

I'd like to disassemble my Quadra 650's power supply to replace the stock fan by a silent one.
I remember disassembling several PSU like this 20 years ago (when I started my collection), but I forgot the how-to procedure. So, I'm afraid of doing it the wrong way and ending up with a PSU that's impossible to reassemble.
I know there are several variants/brands for this specific power supply, but I believe the metal chassis is common.

Any help would be appreciated