[G4] Another Power Supply question

[Thomas DeBoni]

I've seen the discussions on this issue, but never paid any attention to them, and now I regret it. Let me beg pardon and ask for advice.

I have a PowerMac G4 MDD (FW400) that I ran for quite a while packed with stuff: about maximum RAM, an Apple Cinema Display, a SCSI Raid system, three other internal HDDs, PCI cards for SCSI, FW800, etc. While it ran, it was fast and responsive, but it got flaky, and I couldn't stabilize it with a lot oƒ effort and various measures. So, after spending about $250 on useless and nonproductive "professional" repairs, I shelved it.

Now, I'm given to understand the problem may well have been a failing power supply. I don't know how one would test for this, but assuming this IS the problem, can anyone tell me (1) where to get a good replacement, (2) how much it might cost, and (3) anything else an obvious ignoramus might need to know?

Thanks!
Tom