It seem that one of the wipers got frozen, and when I started the wipers one arm moved and one did not. Then they both stopped. When I freed the frozen arm, they seem to move very freely by hand, like they were not attatched to the motor. I can hear the motor running, but the arms do not move. Is there a mechanism like a shear pin that breaks the arms free from the motor so it won't burn out if the arms are not free ?

Thanks for any help.