Micro Metal Gear Motor making wierd sound

I hooked up my micro metal to my explorer phat on my pi zero, and they worked great. For a few minutes. Now one of them makes a buzzing sound whenever it is activated. Anyone know how to fix this? Thanks.

Sounds like the gear on the output shaft is sticking. Try it with the motor not driving anything.

I have, it still spins but no matter what it buzzes