1985 E30 Wiper assembly problem need recomendation

[otto B]

I need a recommendation; based out the video what do you all think is the problem with the wiper assembly. Is it the motor or the linkage? It makes the wipers move in a little at a time and this happens in intermediate setting and when turn of. However, when wipers are used for about 5 minutes the wipers work ok. In the video, I took the wipers off and the cover to see what is the problem, and as shown in the video the sound comes from where the motor and the linkage meet, so I am unsure if it is the motor or the linkage the problem. Any recommendations on what it is?

https://www.youtube.com/watch?v=F0b1SVGvGcM

[superj]

check the ground for the motor