I keep getting check flow on pool pilot digital. Have checked everything multiple times. Cleaned cell, tester manifold spring. Looked at cables, etc. when checking flow sensor, it didn’t seem that magnet was working when manually “activating” flap. Is it time to put in a new tr sensor unit ? Seems like I’ve tried all else. An aside: we had paved patio work done around pool , so there was more inorganic and organic crud in system earlier, but I believe It’s all gone. Earlier in this season, things appeared to be doing fine, though the screen in the system had to be cleaned regularly. Filter sand replaced in 2017. (Also new to forum, hope I can Figure this out)