When you say you killed all 10, you killed those ones in the room with the chariot and not the ones on the other side of it? You don't need to kill any of the gears in the room with the chariot, they don't do anything. I never port up West so I don't know if it's the same, but on East when you port up there'll be a room with 3 gears then a room with 2 gears. Then you'll get to a room with a chariot and gears, and you need to hug the wall to get past this room without aggroing. Then you'll get to a room with 2 gears and then another room with 3 more gears. Kill all those and Homing Missile should do 200-300 damage all the time and no hate reset.
Read his post, he said he killed the 10 "Single-gears" and didn't touch any of the triple gears, which would be the ones in the room with the chariot.
My best guess would be you missed a gear or 2 due to warping and you didn't notice, was it windsday when you pulled them?