TD5 leaky steering box!

Hi there
I have got an annoying dribble from my power steering box (td5), it got more annoying the other day when I had to do a tricky manoeuvre and it spat out lots more than a dribble. Anybody know what the problem might be? Or is it easy to remedy? or is it another take to Land Rover and get charged a fortune situation. Advice/ suggestions appreciated
Steve

if its anything like my 2.5td steering box, I had assumed all I needed was a nice little circular seal like shown in the parts book - apparently it's a professional job only and I have to exchange box for a recon one of about 150 squids.