I just recently redecorated the house and the large north room is now the blue room and a bookcase is where the pinball machine used to be. Since the redecoration, I never saw maid disappear into the pinball machine again, but I did see a maid disappear into the bookcase once. The truth is, when I said the maid had disappeared into the pinball machine, I wasn't being specific to how the maid had disappeared into the pinball machine. What she does is she goes to the lower left of the small centre room and then walks over to the very edge of the small centre room and seemingly stands on the top of the bookcase. She stands there for a few seconds, and then disappears. The maid might actually be standing at the very edge of the small centre room instead of on top of the bookcase/pinball machine. In a few generations, I will most likely redecorate the house again, so just as a test I will not put any furniture in that small area to see where the maid dissapears. It could be one of those common glitches where maids leave the house somewhere other than the front door.