Quoted from gawcol:
No one here that can give me the diameter of the spinning disc?
Here are a set of the clear Tron replacement Disc rubber I ordered from Pinballcenter.eu.
The main disc appears to be about 2 13/16" (inches) for the outer diameter. The smaller inner ring Outer Diameter looks to be 1 9/16" (inches). The thickness of the rubber is approximately 1/16" (Inch).