| There is usually one or more 1.5mm thick dished steel plates in a stack.*The 999RS has four. The curvature is barely*discernable so it is is marked with a* single "dot" (punch mark) near one of it's inner circumference serrations.* The mark is placed on the the concave side of plate curvature and should face toward you when assembled. If there are more, the second marked side faces inboard, outboard etc.
*
You can also check for a dished plate by placing it on a flat piece of glass and then pressing down with your*finger on the outer circumference of the plate.*The opposite*side (180 degrees) will rise off the surface of the glass. | 
Shazaam!
Threaded Mode