Controlling your World the Easy Way

I tried replacing an LM323K with PSU5 No Noise on a Road Show pinball machine. The machine was "working" originally but the LM323K produced too-low voltage leading to resets.

On power-up the machine seemed to try to power-up, and after 3-4 seconds the PSU5 shot out smoke. I quickly cut the power. Attached a photo of the aftermath.

Upon examination it's possible that the teeth of the lock washer bit into the nearby traces. I'm planning to order more PSU5 and try again with smaller nuts without a lock, but had a few questions before I try again:

1. Is it possible PSU5 would fail this way if either/both of those traces got shorted to ground?
2. How would PSU5 behave if output was directly shorted to ground?
3. Is there anything else you can think that I should watch for before trying again?

I did not see your post from 2021, when I posted my thought in 2023 about the possibility of nuts grinding into the board:
viewtopic.php?f=9&t=10402

Well, it's 2025, I recently installed another PSU5 (this time into a Party Zone). I was thinking about this topic again, reviewed the forum, and spotted your post. Your post confirms that we must be careful (but this is true for any circuit or component). It seems we can:
1. Use smaller nuts
2. Flip the bolt, assuming the head is a little smaller; the idea was suggested by @Goiga
3. Use a nylon washer; my approach

Looking at your photo, you retain the TO-3 insulator (pad).
This means your ground occurs at at both nuts on the topside of the PSU5; using my idea for a nylon washer would not work in this instance.