Wiper arm leak

[Georgia Mike]

My wiper arms look like they are not attached correctly. I can see daylight from the inside of the generator compartment so water is getting inside. It has start to rot the dashboard wood form underneath a little in that spot. Is there some sort of rubber washer that is missing?  Also is there a cover for the nut that holds on the wiper? I am getting the front painted and want to get this fixed. 
 

[Gary M]

Maybe missing this?

Edited November 17, 2022 by Gary M

[Dr4Film]

I had my driver's side wiper arm shaft on my Dynasty looking not so good, so I removed the arm with a wiper arm removal tool them purchased a Stainless-Steel Fender Washer that fit over the shaft and tightened it down. The covers are probably available at one of the wiper parts vendors listed in the Monacoers Parts List.