The pressure that our naturally occurring artesian well has maintained for the 13 years since its inception changed about a month ago. The result was that despite the mighty draw of the existing Gould J-Plus 5s pump, the water volume that it was able to lift from the wellhead into the garage where it and the pressure tank sit was insufficient for it to drive the pressure of the water system in the house up above 50 psi, the cutoff on the pressure switch.
It took a week of FREAKING OUT for me to eliminate several possible causes, and two (TWO!) previously unknown pressure leaks in the system before concluding that the pump was worn and needed to be rebuilt/replaced. This turned out not to be the cause, BUT, in a fortuitous twist, ended up aiding in the solution. A replacement J-Plus 5s was acquired, and while being installed, a number of oddities in the plumbing system were also resolved.
Here is the bad boy in all his glory. Too bad that despite being brand new, the pump was still running right at the limit of its pulling/pushing capacity - 22lbs of vacuum. I was able to determine this after installing a vacuum gauge on the 1/4" fill hole on the top of the pump. These can be bought from Granger for ~$10 and are complete life savers, as they tell you what is going on inside your pump.
After installing it in the garage, I was forced to call no joy on the fix, as the new pump was also unable to pull the weight of water that it required from the well head at the bottom of the lot. Jet pumps are cool in what they do, but they are limited to 25' of vertical lift, and I am sure that the vertical between the wellhead to the pump location is right on that line. To solve the issue, I took the old pump (which apparently was not too worn) and installed it at the wellhead. I wired it in to the pressure switch on the pump at the top of the hill so that they turn on/off simultaneously. The result was fantastic. Instead of pulling 22lbs of vacuum, the pump up top barely registers any vacuum on the gauge.