Profound thanks to everyone here who's posted descaling advice. It always read as somewhat daunting, but in the event it was mainly time consuming and a tiny bit nerve wracking. My ECM Giotto (manufactured in 1999, I've had it for about 5 years) seemed to like having its innards cleaned. The solution (I bought citric acid from a winemaking supply store and diluted it in warm water) that came out had virtually no solids, but based on the fact that the gauge works again I do suspect there was some gunk in there. Also now have a much stronger flow from the hot water outlet. I think there's more pressure in general, so I might go in and turn it down a hair (getting some pock-marks on my puck). Thanks again!
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