I have a 90 420sel that had the exact same problem. I tried power steering fluid with stop leak in it because my problem was very, very, minor. It got worse. So I priced the new boxes too. I ended up puting a box off of a wrecked 420 for $180 plus $85 labor. My leak has stopped. I got my box from www.actionautowreckers.com. They gave me a 90 warranty with mine. I saved over $300 by going this route and I figure that if if it will last me a couple of years or so, it was worth the savings. Maybe next time I will replace with a brand new one. Hope this helps. Also, I do agree with the others that if you are leaking pretty bad now, you need to get it fixed soon to save some of your other parts and possibly save your life in case the old box was to completely give out. Oh, I have seen also on ebay a couple of remanufactured boxes with warranty for about $275.