The photocopier broke down yesterday, but now it's OK. (it / work / again; it / repair)
I've formed (or built?? Correct my English, please!) this sentence:

It works again; it has been repaired.

But the key (at the end of the book which I took the exercise from) says that the following sentence is correct instead:

It is working again; it has....

Why is the present continuous tense to be used here instead of the present simple? Could I use the present simple in the context as well? Would it be correct?

Please, correct my English!! This is the only way (or at least one of the most important ones) I can improve it.