just pull up to the kerbside, make sure you have too much soap in the screenwash bottle, put the lights on and pull the lever!. great fun for spraying annoying teenagers with hoodies on. My laser blue GTi used to have a extremilly powerful jet!.
I dont know why would you wanna inspect them , if both are jetting water on the lenses then whats the problem??. like whats been said, you could bust the motor and nozzle jets.