If the steam wand is leaking the valve o-rings are worn out. To replace the o-rings do the following:
1. Turn off the machine, unplug it, and allow any built up pressure to dissipate.
2. Remove the top cover by loosening the Phillips head screws.
3. Locate the steam handle hex screw on top of the black handle and loosen the screw, 5/64ths Allen wrench, I think. No need to completely remove it.
4. Rotate the handle and valve shaft out of the valve and out through the valve opening in the Barista. The valve shaft has two o-rings in grooves about 1/2 inch back from its end.
5. Take the valve shaft to your local hardware store and ask for replacement o-rings. They are 5/16x3/16x1/16. If you are nice the clerk might remove the old ones and replace them with the new ones. Allow them, removing and installing those o-rings is the hardest part of this job. Rub some hygenic silicon grease on the installed o-rings.
6. Reverse the above for assembly
7. Voila, you are ready to turn on your machine and have a coffee.