I ordered a replacement power supply directly from the Buffalo store and they sent the wrong one for my older Quad NAS. They do not send the power cable, only the transformer, so I couldn't use it as my original power cord has 2 pins while the new one requires a 3 pin. Trying to return it was an excercise in futility as there is no way to directly contact them and I believe this is done on purpose. I was about to start a charge back with my credit card but found a post on Amazon where someone else had the same issue. He said he used a power cable from an old laptop adapter so I checked and I had an extra one as well and it worked. I've been up and running for over a week so I think the issue was definitely with the power supply.
But, the Buffalo store can go shove it and I will never buy or recommend anything from them ever again. Multiple emails sent through their website where you get a canned response from an unmonitored email address (it doesn't accept replies) and they still never acknowledged the problem. For $50 I got a standard power adapter that I had to dig into my own stuff to get it to actually work. They should be ashamed of themselves for this type of treatment of their customers.