I scored a barely used MES on Craigslist for $80. This one doesn't have a vent on the top. I'm thinking about cutting one in. It seems that most people on here leave their vents open for taste and health issues. I can't imagine that it would be good to have the same smoke trapped in there the whole time. Is there wiring in the top of the MES? What size of hole saw should I use? Anyone else done this before? Also, I was under the impression that they used rivets on the back, because I remember reading people's recommendations to drill out the rivets and replace them with screws so you can access the inside for repairs. This one has screws already. The guy I bought it from said he didn't modify it, that's how he bought it. Thanks in advance for your input.