Sounds vaguely familiar.. LOL
That in an odd way reminds me of a problem (years) ago when I had to go to an MOD site to figure out why a page printer (LED not laser) was producing garbled printouts from a mainframe it was connected to via RS-232.
The slight complexity was there was no separate "flow control" on the host systems serial interface, so it was all running via XON/XOFF.
Off I went down to the site in the South West - one of those with soldiers on the gates with real guns loaded with real bullets! - complete with an old "luggable" RS-232 protocol analyser with built in 5" CRT. Everything seemed ok, except a lot of the XOFFs which should have been sent by the printer to tell the host system to shut up for a bit, seemed to be being ignored or even missing.
One of our field engineers had been down to it twice and changed most of the controller boards - the serial interface board had been replaced 3 times. All to no effect.
Bit of thinking then out came the multi-meter and onto the PSU. The +12V and -12V outputs were somewhat low (less than +8V and -8V respectively). Turns out that those voltages, only used by the serial interface, (standard RS-232 signalling levels) were just too low for it signal reliably to the host system. So it just wasn't "hearing" the XON/XOFFs.
New PSU, with the correct outputs and normal service resumed.
And I got to "chaperone" one of our other printers on the same site which was going through "naval submarine" validation testing. Basically subjecting it to various shock levels (on a huge shock table) in various orientations to ensure:
1. It worked up to a certain level.
2,. Above that it didn't have to work but nothing had to fly off (simulated battle conditions).
And the last test - see just how stood up to "destruction level shock testing". Basically give it the highest level shock and see what happened. It was prettyy buggered inside, but only the main "smoked plastic" cover flew over 15 feet away, a couple of knows flew off and something cracekd. Otherwise stayed pretty intact.