yeah happened to me in my mini T motor.....i opened it up and cleaned the com....too small to cut lol....and i got some other brushes from another motor n swapped em over.....runs like a beauty till it stuffs up again lol.....
its from the carbon (or wateva material the brushes are made from) builds up on the comm and makes it have a crap contact with the brushes
FG leopard comp w/Trevor Simpson 28.5 bzm crank
HIP Baja 5sct
AE tc5 3.5t speed monster,Futaba 4pks
Raptor G4 ,Raptor e550,Gaui x5,Mini titan v2,Precision aerobatics bandit 4s monster,Carbon z scimitar Jr 11x