Заполните пропуски в инструкции следующими фразами
If the commutator is dirty, 1_______.
2_______, clean them with a pin.
If the brushes are worn, 3_______.
4________ are clogged, use a small file to clean them.
clean it with a petrol-moistened cloth.
If the terminals are dirty
replace them
If the grooves on the commutator