I am trying to replace my rear window wiper arm on my 2005 Mitsubishi Endeavor. There is a busted off piece of the old one still on the shaft. I cannot put the new one on until this piece comes off. I don't know if this part of the shaft is splined, threaded, or straight. I'm afraid to put any torquing pressure on it for fear of ruining the motor. How does this little busted piece come off? Threaded or straight off? I have attached an image. Thank you.

 

Bump!