Did you do all this while you were supposed to be delivering mail?
I have a spare heavy-sixer that is shot. I might do this. Those Atari paddles are terrible. I have two sets, and I think only one of the controllers works properly. The rest of them have potentiometers that are completely messed up.
The only thing I was thinking I might do differently would be to cut long slots into the top of the case, in lieu of cutting a hole for a vent hole. I would then reinforce the remaining plastic with strips of aluminum or steel. Do you think it would vent enough heat that way?
Heh -- this was my nightly after work project in my work area away from children - IOW my little moment of Zen. As for the paddles, the problem of one bad paddle is common, because most games only make use of one. The easiest solution was to swap the paddles on the cable, exchanging player two for player one.
Heavy Sixer - you'll need to make a few different case cuts to get it done - And you wont have to deal with the spines on the inside of the top case lid. They dont exist on that model. I tried venting the case as you suggested, but it didn't work. The case lid starts to sag where the openings are cut - though your suggestion of reinforcing the remaining plastic with some metal might solve that. You'll also have to approach adding the joysticks and power connector differently, as the Heavy Sixers have those connections mounted at the bottom-center of the case on a separate daughterboard.