I was out there this afternoon, cleaning the hole in my Rainwise gauge. The screen that covers the hole helps out leaves and pine needles, but doesn’t keep out the black gunk. It happens often enough that I modified the cotter pin that holds the screen so that I can remove and insert the screen without having to open up the rain gauge.
Slow rainfall is a sign of a possible clog. Today’s slow rainfall was a false alarm - it really was just slow rainfall. The sure sign is when it continues counting after the rain has stopped.