wipers slapping top and bottom

Hi, I have a problem where my wipers when on constant at any speed and when screen is wet. Basically they slap both the bottom and top trims of the screen so moving them 'round on the spines wont help. Has anyone seen this problem and know teh cure?

Cheers,

- Douglas

Just checked, it's all very tight; BTW, playing with it it is only the driver side which 'slaps'