In article ,
"mc" wrote:

"William Sommerwerck" wrote in message
. ..
When someone says their Selectric is suddenly typing the wrong characters,
I
wonder whether this is a troll.

The ball can be put on only one way, and locks in place. It isn't clear
how
it could suddenly slip.

Teeth broken off the bottom of the ball are another way to get wrong
characters.

True, but I've seen balls so used that the metal plating was mostly worn
off, but with intact teeth; I don't think there's any way for them to
get broken while installed.

(That Selectric had been used in an airline reservation system; there
was a "crater' on the platen at every possible character location.)

Isaac