Those not wanting a saga can skip to the last paragraph, but here's some backstory.
Waiting patiently for a 34401a to show up for a reasonable price as a "parts only" fix-er-upper as my first vintage repair, I was surprised to snag a grimy-looking but working HP-branded (w/ black low input shrouds) shortly after it came up for sale.
I picked it up from the post office and wondered what the beat up box would contain, especially as the thing was sliding back and forth in the (not-too-oversized) box containing it just while carrying it back to the car.
Minutes later, I was home, opened the box, and the first thing I noticed was several popped (large) air pocket packing bubbles. 3/4 were flat iirc. There was a layer of bubble wrap, and some other newsprint wads too, which is probably the only reason the thing works (spoiler!). I also noticed the power button jammed (and unyielding) between the front edge and rear edge of the front panel, and heard things rattling around inside -- they sounded like small things, so I knew at that point after wiping this thing's years of grime away, I'd need to crack it open and clear it for safety before plugging in.
Fast forward through sink and suds (for the bumpers) and we're at the bench. The cover was a lot more difficult to slide off than I've seen in the few videos where these get opened up. Two small pieces of plastic (smaller than a fingernail) fall out. The power rod was dislodged from the actual switch (on the back side of the unit near mains entry), so I jostle it around gently, and get the button to pop back out the front, and then mate it up w/ the switch, but am confused when the switch won't operate freely but sticks, and not just a little. It also sucks the keypad membrane back along with it when it's depressed.
I sort all this out by loosening the front panel screw, and letting things mate with each other, and the button moves freely now, so I tighten the front panel back up and all seems fine. I spot the area where the plastic pieces came from: the front panel's rear edge a the bottom near the inputs. NBD, cosmetic, so I close it up and plug it in to see if it works.
I ran it all afternoon and things seemed fine. I can't test HV, but all the basic functionality tested fine, as did its self test. The display was bright (almost too bright), the lens was perfect, and the cleaning I'd given it made me think it'd look totally brand new if it had been packed better. The seller and I exchanged some messages (initiated by my "item arrived damaged" ebay doings) that began before even powering it on (w/ photos), and he seems reasonable and committed to the legwork for a USPS claim.
At night I spend time poking around on the inside to do a more thorough inspection and don't see much to fret over. Along the bottom of the board, I see an anomaly that I gently clean up with some IPA and, after a few swipes, up comes some copper foil within a guard trace. Guess I just undid someone else's fix, I thought, and without any fuss (I wanted a fix-er-upper anyway, right? I put a single strand of copper down w/ some trusty 63/37, cleaned it up, and took some more board photos before I saw what I couldn't believe I missed.
The board had somehow bowed up and was sitting atop one of the chassis retaining "hooks"! Jesus, how had I not realized 45 minutes ago, I thought as a sense of panic and urgency now set in to de-stress the board and all its magical doodads. This board torque explained why everything up front had been so cockeyed, and why the front panel needed to be loosened a bit for everything to mate. I'm of the mind that it certainly wasn't this way prior to packing; I trust that the (single) photo of the unit, with its power button sitting where & how it should, was taken at the point when this went up for sale. But geez, the Gs that must've been required for this to even happen, right?! It even managed to make the front bezel punch through the rubber bumper. So, I got it back where it needed to be after partial disassembly, and regretted running it for a whole afternoon w/ the board bowed right near the ASIC and the voltage reference. Should I worry? Things still work. Pics follow. Should I gently reflow w/ some hot air? Should I just leave it alone unless it stops working?