Elektron was kind enough to send me a new power-supply board. It took a while because they were away at NAMM, and then they were out of boards so they had to wait for the next batch to be manufactured. However, the upside was that I didn’t have to arrange to ship the Octatrack to California; and because the problem was intermittent to begin with, I was still able to use the Octatrack while I was waiting.

Replacing the board was trivial: 10 screws and four connectors. It seems to work fine now.

Yay!