I don't know how they wrote this with a straight face.
This apparently was a real memo sent at a computer
company to its employees in all seriousness...This
memo is from an unnamed computer company. It went to
all field engineers about a computer peripheral
problem. The author of this memo was quite serious.
The engineers rolled on the floor! (Especially note
the last sentence)

Mouse balls are now available as FRU (Field
Replacement Unit). Therefore if a mouse fails to
operate or should it perform erratically, it may need
a ball replacement. Because of the delicate nature of
this procedure, replacement of mouse balls should only
be attempted by properly trained personnel.

Before proceeding, determine the type of mouse balls
by examining the underside of the mouse. Domestic
balls will be larger and harder than foreign balls.
Ball removal procedures differ depending upon the
manufacturer of the mouse.

Foreign balls can be replaced using the pop-off
method. Domestic balls are replaced by using the
twist-off method. Mouse balls are not usually
static-sensitive. However, excessive handling can
result in sudden discharge.

Upon completion of ball replacement, the mouse may be
used immediately. It is recommended that each replacer
have a pair of spare balls for maintaining optimum
customer satisfaction.

Any customer missing his balls should contact the
local personnel in charge of removing and replacing
these necessary items.