First of all, it is 1998,Chevy,1500,Ext Cab,Short Bed,5.7l,V8,350, I am having problems with the wiper motor on the 98. It has its own mind.

The motor will work when it is not raining and when it rains. It will work when it wants to work. If I tap it a few times. It will start working again. How do I replace the wiper motor? Thank You For Your Input.