Drivers side wiper

I have a 2000 blazer. The drivers side wiper shaft is worn smooth. I can tighten the screw and it will work for awhile. Can it be fixed or do I have to replace the motor. If so how do you replace it? Thanks for your time.

Try putting some BLUE loctite on the tapered shaft then reinstall the wiper arm. It might give enough extra grip to stay secure.