Sprinkler leaks broadly speaking manifest as soggy spots, low force, or effervescent at heads

https://elliotdnfg497.cloudhinter.com/posts/winterizing-your-system-crucial-sprinkler-upkeep-tips

Sprinkler leaks on the whole show up as soggy spots, low stress, or bubbling at heads. Inspect risers, lateral strains, and valves, then restore cracked fittings to restore device functionality.