First thing I would check is that the bottom of the rain collector bowl isn’t blocked by bird droppings or other debris.
After that, I would try running some water through it to see if you can hear the tipping buckets move back-and-forth.
If you don’t hear them tipping, then you’ll need to open it up and see what might be blocking their motion. Common problems are spider webs and wasp nests.
If the buckets are moving freely, but rain still does not register, you’ll have to consider something like the reed switch might be worn out or mid-aligned.
Sent from my iPhone using Tapatalk