Step-2
Locate the heavy part of the back-plate at the bottom...and remove material as necessary. I used a drill-press.
Remove material from the very bottom...at the 6-oclock position, each time....this will change a bit as you go, but don't worry about it. Always remove material from the 6-oclock position...a very little at a time.
Continue to balance the back-plate...until no matter how you position it in the stand...it doesn't turn. Now you have perfect balance of the back-plate.