Just found some flaws in the saco and 3 ways to add a fast ground

[Hydros]

adding an ground terminal is questionable, if the brush plate itself is not securely grounded.  Note on the image, if the inner casing is coated with an anti-rust solution, then there is the possibility of less than a 100% solid ground.

It may be best to solder the brush plate or use screws, washers and nuts to insure a 100% tight fit.

Also, the 3 hold down holes would be ideal to attach a ground strap with a soldered on ground terminal.

[Hydros]

I am guessing all that chrome is not the best surface to transfer volts and amps