I picked up my 4" missile command trackball from Lloyd at the CoinOp warehouse in Hagerstown MD. for 10$. I also ordered the 4" red translucent ball from Happs. I still need to get some replacement bearings for it though.
-PMF
Is it really 4"?
There seems to be some confusion about how big the Atari Big Balls really are. The first Atari (football, 1978) trackballs were 4.5" Is this the same size as the Missle Command ball, or was it the first step down towards modern small balls?
I measured my Atari football balls a few times while I was trying to acquire new rollers for them. They are pretty close to 14 1/8" around (circumfrence), which makes them 4.5" tall (diameter).
The guy who makes the rollers insisted they were for 4" trackballs, but they fit my 4.5"s perfectly. It is more than possible that Atari used the same mechanism with a half inch smaller ball in it.
Just a curiosity thing.
If they are 4.5"s and you got the whole thing for $10, please tell me how to get in touch with this Lloyd person immediately!

Al