I rented a Bluebird aerator on Saturday. It had a roll over safety turn-off switch. The switch was so sensitive that it turned the aerator off on the slightest incline. I had to aerate up and down slopes, but even the angle on my turn arounds would shut it off? I had to restart it at least 50 times on one lawn, the rest were pretty flat but probably 50 more shut offs on the other five yards. Do all aerators have this feature or only rental or Bluebird? During the off season I may have rotator cuff surgery from pulling the rip cord on that baby!