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