When I was in high school, I took Drama for two years. It was one of the few classrooms that was carpeted. This would have been 1978. There was a brown Model G Electrolux (straight suction / no power nozzle) in the classroom. His name was "Homer". If you got to class after the bell rang, you had to "Homer" the rug for a minute or two. No one ever changed Homer's bag. They had the automatic control set at six. Of course, Homer was very quiet in operation because the bag was so full. They were using the floor brush side of the nozzle, since there wasn't enough suction to use the rug side. One day, I brought in a new bag. My Aunt had a Model Automatic F (with PN-1 - very rare for the time), and I asked her for a new bag. Homer's front door was taped shut so he wouldn't open up (they thought he was broken). With the new bag, Homer sucked and sucked for about ten minutes - until the new bag was sufficiently clogged with all the fine dust that had been accumulating in the carpets for years. Then, he triumphantly popped open again. Out came the tape, and I think that was the last new bag he ever got.