How can i fix my washer jets on my Alfa Romeo 156?

My washer jets on my Alfa 156 have stopped working. I have tried cleaning them out with a pin but it has made no difference. The pump sounds like it is working and there is some water coming through but it doesn't reach the windscreen. I recently had my windscreen replaced and the problem has got worse since then. I don't think the line is split as there isn't any water leaking out. Any ideas for a quick fix before i have to take it into the garage?

Mark Dunne
January 2008