Front windshield washer sprayers not working . . .

[exsterminator]

They make a noise as though they want to work but no fluid comes out. The reservoir is full, one nozzle kind of dribbles some fluid, the other does nothing. Don't know if it is the motor as in this thread

http://www.xoutpost.com/bmw-sav-foru...-everyone.html

as it definitely sounds as though it is cycling. Merely blocked perhaps and if so, how do I clean them out? Other ideas?

Thanks all