Windshield wiper "nut" where arm attaches got stripped out and cannot find the part to buy to fix the problem. Do I buy the wiper motor and linkage. It appears to all be machine pressed into one part? Any help in what part to look for...

 

If it's the threaded part then go buy a die to re-thread it or are you talking about the cone shape knurl part the make the wiper actually move?

 

Go buy a new "NUT" any hardware store