With a little brute force and ignorance I was able to get the arm off of the gearbox. This will give me a chance to clean up the splines and grease it up before reattaching it with a cutter wheel. I plan on cutting the arm off, but will trim it down into a circle.
I do like how Chris S set his chunker up and because this appears to be the same gearbox, I plan on making mine similar to his with his permission.
After placing this back on the arm, it appears that it flexed back to be too tight. This means I need to tack or completely weld the the cutter on this while it is on the shaft. The cutter’s back plate will keep it from being pushed too far towards the gearbox. The bolt nearest the cutter will be worthless after it’s welded together.