Before panicking, try bleeding the steam wand to see if the machine then heats up properly. Some kind of air lock, apparently, can cause these symptoms.

There may be a simple solution to your problem. Another thread here went step-by-step through all the possible causes-- crapped out pressurestat, inaccurate gauge, etc. In passing, one poster mentioned somthing about an air lock.

Machine was turned off for a couple days, then turned back on. Usually on 24-7.

Opening the steam valve, very little steam came out and the pressure rapidly dropped. Odd. This machine is a dragon with plenty of steam power.

Left the wand open to verify pressure buildup, which did occur. On closing the wand, the heater continued working, and the temperature began steadily climbing per normal, leveling off in the low 200's also per normal.

This particular set of symptoms was confusing, and I couldn't come up with a viable hypothesis that didn't involve hundreds of dollars in repair parts. I hope this helps someone.

beanfish wrote:Some kind of air lock, apparently, can cause these symptoms.

See Can someone please explain false pressure? for why bleeding some steam from the boiler helps.

Very helpful, Dan. Thank you.

The machine is a Bricoletta, which does have a vacuum valve on top of the boiler. Might it be the case that I should have a look to make sure it is operating correctly, or, possibly, to simply replace it?

Again, thanks. I think the explanation provided makes perfect sense.