Quoted from hocuslocus:why does the second playfield plexi get so cloudy? I'm sure it's a pain to get the bottom playfield off. The only ACDC I've seen, is near my house and the bottom playfield looks horrible, the rubbers are about gone. Once you loose the ball, it doesn't kick it out again. you have to wait till the timer zero's out.
4 or 5 screws and half a dozen plugs and the lower playfield comes out. I take mine out on average once a year to clean n renew things.
Opto across the bottom playfield that see the ball drain probably dirty, lots of build up around that area.
I heard the cloudiness is something to do with the rollers running over the playfield before the clearcoat goes down, something like that.