Good question. I’m still waiting on an official response. I learned from field testing different coatings that I shouldn’t touch the coating since it was delicate. At least I learned on a field test unit. In your case I would have just blown the water out. It is water hanging on the sonic transducers and/or large puddles on the lower plate which causes the issue. There are algorithms in place to reject the results of smaller water droplets but it is too much to filter out when a large amount of water stays and doesn’t get blown out.
As far as cleaning, I have just carefully reached in with something to get things like cobwebs out without touching the coating. Water is the only other thing to maybe squirt in the gap. I have a SKY I need to clean off bird poop from today when my Bird Spikes get here and I plan on using only water, maybe a soft stream out of a garden hose.