I have a small (1v5) DC motor which I plan to use. It was used, and appears to have a small capacitor soldered between the leads. What exactly would this do? My guess is make it run for only a short time after power is applied before short-circuiting, but it seems like that would be counterproductive.
If it's connected across the leads (i.e. parallel, not series), then it's purpose is probably to prevent the motor from stopping dead if power is cut, instead making it slow rapidly. The capacitor would only cut it off if it was connected in series, like between one of the leads and the power source.
At least, that's what general knowledge and Google think, and they agree.