I think, building a DIY powersupply is only a thing for well experienced DIY persons, as it involves mains voltage. And people able to get this done in a secure way will know how to repair or build a new one.
I would go for a new PSU ordered by your Moog distributer.
Unplugging my PS in the dark, on the floor, I was pulling on the wrong cable & since it takes a bit of effort anyway, I strained the hardwired part & exposed some wires. It still works, but I need to repair/wrap them up.
I had my power supply replaced after just one year. Possibly it could be the same issue as with your power supply but I never checked, just checked if some fuse was blown. It had a spiced price tag but as the power supply is crusial for the sound, I guess, I ordered a new from Moog.
did you ever fix this? just curious cause i have the same problem. minmoog just went off spontaneously during use, won’t turn on again. Hoping its only the PSU….