Print contaminated by chips of previous filament colors I have a flashforge creator dual.

From time to time while printing a model I notice when there are abrupt changes in direction, that a few "Grains" of old filament fall out from the head.  Generally they end up embedded in the print which is not a big deal, but sometimes they get into a visible portion.

I can mitigate this somewhat by disassembling down to the gears, and blowing out all of the old filament.

My question is two fold
"What is causing these chips to accumulate near the gears?"

"Is there something I can do to resolve this issue?"
My bet is your extruder knurls are scratching the filament. If it happens for specific filament then probably it doesn't keep its diameter. It means you can avoid these grains by using better filament.

If it happens always then you could do 3 things


reduce stress on the spring which pushes filament to extruder gear
make extruder gear less sharp
eventually change the great itself