Sprinkler leaks almost always seem as soggy spots, low pressure, or effervescent at heads
https://finnsder796.almoheet-travel.com/winterizing-your-system-important-sprinkler-maintenance-tips
Sprinkler leaks in the main seem as soggy spots, low tension, or effervescent at heads. Inspect risers, lateral lines, and valves, then restoration cracked fittings to restore approach efficiency.