Do you know how to troubleshoot low pressure at the 9-port water valves of a Paramount self-cleaning popup system?
The 15 popups used to work just fine, in that a handful of Paramount popups popped up, rotated about 1/16 of a circle, shot water for a few minutes, and then popped down, awaiting the next cycle about 15 minutes later. Meanwhile the next handful of popups went through the cycle, and the two permanent pop ups fed the deep end catch basin where the main filter drain lies.
But, now, the pop ups are barely popping up, due to, for some reason, I think, low hydraulic pressure.
Up on the deck, there's used to be something like 25 psi on the first water valve, and the second water valve had fluctuated half the time from 0 psi to something like 20 psi the other half the time.
But now both on-deck water valve gauges read zero psi even after I replaced one gauge and swapped them - so I know the gauges are telling the truth.
Therefore, I know I have low pressure at the water valves - which explains the low pressure at the popups - but how do I debug low pressure at the water valves?
Back below deck about 8 feet below the pool at the cleaner pump, water is sucked in from the skimmers into the cleaner pump, and then pushed to the water valves, which regulates which handful of popups are activated in sequence. All the Jandy valves to the cleaner pump are working, as I've disassembled them all (after repairing some unrelated leaks in the plumbing).
I've disassembled the cleaner pump itself, to replace the seal, so I know the cleaning pump impeller is just fine.
If I leave an inlet side valve open to the cleaner pump, water pours through without obstruction (all three pumps are 8 feet below the pool); and the cleaner pump basket is clear of debris, as is the inlet to the impeller. (Note that the cleaner pump water flow is from the skimmers, to the cleaner pump to the water valves to the popups, so there is no filter involved and no valves other than what is visible at the pump equipment for inlet and outflow to and from the cleaner pump.)
Back at the pool, no popup head was ever moved to a different location than original, and, they are all are in their holes and sized properly (since the system used to work just fine).
After draining the pool a few wekes ago, I removed all the popup heads, snaked, and cleaned out all debris (there really wasn't anything to speak of), and tested manual spinning operation of each popup in air.
Opening each of the two on-deck 9-port cleaner heads, I don't see any stuck pistons, nor obvious debris or broken plastic gears - but these things are complicated inside.
Any other suggestions on how to debug why there is low pressure at the measuring gauge on each water valve?
Note: There is no vacuum in this pool. The filter system is separate from the cleaner system. The filter system filters out suspended and settled particles and debris and the cleaner system stirs the pool so that the filter system can suck in all the suspended and settled particles and debris.