Quoted from ballbaron:
I know it's been a while since your post but is there a way to remove one of the magnetic features and find a manufacturer ID on the magnet itself?
Not exactly how it works. The "magnet" is a non-magnetized solid steel core inserted inside a copper-wound coil produced by whomever made the game, Stern, JJP or WMS. It's very doubtful that the same game would have manufacturing tolerances in the coil beyond a couple percent, and that would not affect the ball getting magnetized much quicker or slower than normal.
Remember, every magnetized ball report is anecdotal and there is no evidence via a controlled test that a Ninja ball can get magnetized as quickly as some have said. I wouldn't waste your time on it.