Diode Usage In Small dc Motor: Why ?

Hi Folks,
I'm not an EE, so would really appreciate someone educating me a bit on this.
Trying to fix kids toy.
Very simple electrically, just a battery going to one of those
small, cheap, probably a PM type, dc motor that does nothing but spin a pointer.
For some reason, they have a diode in one of the leads to the motor. (in series with one of the leads)
The Diode must be defective, for if I by-pass it, the motor spins just fine.
Can't imagine why the Diode.
Hard to believe that it is for any RF suppression due to the brushes that are apparently on this really small dc motor ?
Anyone have any thoughts perhaps as to for what purpose the diode was included ?
Thanks, Bob
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What kind of toy? Is it to keep it from spinning backward if the battery is in there backward?
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     snipped-for-privacy@aol.com writes:

or possibly to prevent it applying voltage which might destroy the driver circuit if the motor is spun by hand so it operates as a generator.
--
Andrew Gabriel
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