squirt

A few months back the C32 started to need two pushes of the windscreen washer stalk in order for water to come out. It was like the first push primed the system, and the second push squirted it! Dealer diagnosed it as a faulty one way valve, which was letting the washer fluid drain back...

just a dribble motor is buzzing ok no dirt in the squirt eyes could the filter in the washer bottle be clogged?? how do i removwe it cheers 220cdi model