Not working, briefly, 4 letters
On the fritz, 10 letters
Unsuitable for surgery, 10 letters
... the beginning of a spy?, 11 letters
Kaput, 11 letters
Needing fixing, 11 letters
Not running, 11 letters
Not working, 11 letters
Won't run, 11 letters
The quality of occurring at an inconvenient time, 15 letters