Rain sensor not working properly - 2002 X5 3.0
 

I recently noticed that my rain sensor is not working properly. Previously it would sense the amount of rain and adjust the rate of wiping accordingly.
Now it just keeps the wipers at the lowest setting. The wipers swipe once every 10-15 seconds, as you ca imagine in moderate to heavy rain, that can be an issue.
I haven't had any work done on the windshield. Is there a way to rest the sensor function?
Thanks all.