how to fix my washer jets?

hi, my front and rear washer jets are not working on my renault megane coupe 1999. i have filled with screen wash and when i pull the lever i can hear the pump going but no water is coming out. could the tubing be blocked and if so how do i fix or replace this? i have also used a needle on the nozzle but still doesnt work.

thanks in advance

mark mccabe
January 2009