If you can, get some pictures of the part you're talking about, and try and work out exactly where the leak is coming from (pictures of the leak origin would be best!) However from your description Im fairly certain you're talking about the vacuum pump. Mine leaked from there as well. You can replace the O-ring on the vacuum pump which should solve your leak.
You can do it yourself depending on how handy you are, take the battery out to give more access. When you have replaced the O-ring and are reinstalling the vacuum pump don't over tighten the bolts - trust me.