Years ago, we got a "Dampfente" - which is a small hand-held steam cleaner that has, more or less, the shape of a duck. It's not large, and it has been used occasionally through the years, mostly related somehow with textile work.
For instance, I used it to set the twist in spun yarns when I was pressed on time; steam once, let cool and dry off (which will not take as long as letting a thoroughly wetted skein dry out) and then repeat the process. Voilà, almost instantly dead yarns.
An added benefit of that process was that I realised how much movement and wiggling happens when the twist is set. There was a lot of wiggling of the threads, even though they were all stretched on a skein winder.
From the past tense used in this past text, you can probably guess that at one point, the little duck broke down. It would still heat up, the pump would still try to do its work (audibly, but not horribly so), but no steam was coming out.
Yesterday I finally took out a screwdriver and some ambition and took the whole thing apart. I got joined in my duck dissection by The Most Patient Husband of Them All in the evening, and using four hands (which is very much to recommend, since the hot parts have to be kept away from the possibly-melting parts, and the water from things that should keep dry, and you have to test all the stuff somehow) we found the culprit: The filter was clogged.
I had expected some limescale issue to be the cause, but no, there was nothing. Instead it looked like enough fine fibres and dust particles had accumulated in the fine filter mesh to stop water from coming through. Filter cleaned, set back in, then a longish session trying to fit everything back inside into its proper place and screw the thing shut again.
The fibres in the filter probably came from not cleaning the little can that was provided to fill the duck with water well enough before using it - so fibres and dust from the bottom of the little water can got into the tank, and from there into the filter, and there you go. Clogging, after a while. Which means in the future the water can will get cleaned before use (with normal water) and just to prevent any chalk issues, distilled water will be used.
I'm very pleased now - both that it functions again (it will come in handy at the Textile Forum, I'm sure) and that it was possible to repair it!