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, but the engineers rolled on the floor:

"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 suspect local personnel of removing these necessary items."