If your rain sensor won't stay on the bracket mounted to your windshield, the likely cause is a lost “TAB B” which slots into the front of the sensor casing and serves to secure the casing to the bracket.
“TAB B” is not sold by itself, you need an entire rain sensor assembly. Or print this, either way!
Recommend PETG or ASA for heat tolerance.
Designed and printed after I had a windshield replaced and the shop lost the tab…..
The author marked this model as their own original creation.