Always give those things the benefit of the doubt. Pulled a non working one apart, drained the mud and water. Removed the rust an corrosion with a brush and sprayed liberally with wd40. Had zero expectations based on how it looked when I opened it. Little bugger fired right up and works like a champ.

 

Never had one that I could not revive, normal failure mode is a rust seizure. BTW, I coat the armature in marine grease before putting it back together.