I always carried a couple of USB sticks with software, licences and documentation on them - one in my carry-on, one in a zippered pocket - and extra interface cables &c so that if everything went oops, I could just borrow a laptop at the client end, install my stuff and get going in a few cups of coffee's time.
Most interesting experience: A customer managed to store their spare parts ashore (!), and we found the reason a big oceanographic sampling system didn't work was because a very proprietary plug inside a data acquisition device hadn't been properly inserted during assembly, damaging the connector beyond repair.
We wound up having to disassemble a small DC motor (to get at the lacquer wire - very, very small cross section!) and hand solder jumper wires onto each of the 88 pins on the PCB.
Took us a few hours, each of which cost our client on the order of $7k in fuel and crew wages, but it worked in the end, ship's electrician and I taking turns getting those pesky, small wires in place without upsetting the work we'd already done.
Soldering .02" pitch connectors with a bog standard Weller iron is a character-building experience. It gets better once you've tacked a needle onto the tip, though.
The alternative? Taking the whole vessel back inside helicopter range, then airlift a $5 plug out (Oh, and a crimp tool! Might as well bring a spare plug, too. Just in case.) That would have cost significantly more than the downtime they had while we were soldering.
Having the spares aboard so that we'd be looking at them instead of for them when we figured out what was wrong? Ten minutes of downtime, $5 in parts, done.
I'm going to bet they /never/ had to use those spare parts before and thought they were dead weight.
Happens everytime. That box of cables you threw out last week because you never opened it in the past 20 years? Yeah, something just broke and you need one of those cables now.
Happens. Every. Fucking. Time.
And everyone wonders why I look like a chronic hoarder.
The problem is rather - I'll just let my prejudices roam freely, my apologies - beancounters who realize that it is a waste to keep X sets of spare parts on X ships, when they are hardly ever used - heck, much more cost-efficient to keep one set of spares in a common location, then dispatch as needed.
Except, of course, that 'dispatch' is non-trivial if you're, say, doing core samples along the mid-Atlantic ridge...
— Why are you carrying this around? You won't need it.
— Exactly so that I won't need it.
(Works well with umbrellas, leathermans, band aids, etc.)
I'm guessing mechanically secure it with something heat tolerant (steel wire) for most of the tip length + lube the interface with molten solder? Then crank it to 11 to get enough heat to the tip?
Or spin the needle inside the hole until it welds itself.
Then you start soldering, after a few successful ops you figure this is going to be a walk in the park - and are promptly attitude readjusted by a blob of solder dripping off the iron and onto your PCB.
Did succeed in the end, though.