As Patrice said, the solution is use Janome or Organ needles.
My 6600 will use any needle, but not the 8900. It almost drove me mad at first. Until I bought some Janome purple needles - end of problem.
My machine doesn't think much of the Janome red or blue needles either. I have to use the purple, or Organ HAx1SP Super 90 originals. These have the snake tip same as the purple Janomes.
Piecing and fmq is now a dream on it.