Mice can start acting erratic for a number of reasons. First, we
will try the easiest solutions. Often the "Male" mouse ball or roller is
dirty, this means opening the trap door and cleaning. The roller
normally only requires a fingernail to scratch off any accumulation of
skin, dust and body oils. The mouse ball can be cleaned by removing the
ball and cleaning with water or very mild soapy water.
If the above does not fix the problem, or if this is a female mouse, the
problem is normally a break or short in the tail. For those who are
adventurous, or can't afford to replace, now is the time to break out the
multimeter. With the multimeter, you will be needing to test continuity
of the tail. Be patient, as you will often need to dismantle the mouse
and disconnect the tail from the circuit board (or not depending on age).
Often this is most challenging because the colour codes don't reflect any
specific pin locations. Record the pin numbers and colour codes for later.
At this point if it's only 1 broken wire, with an assistant ask them to
slowly start flexing the wire in 1 to 2" lengths, when you suddenly have
continuity you've found the damaged section.
In the best case you will simply be shortening the tail length to bypass this
point, otherwise you will need to wire up a new tail to completly replace
the old one.
If you find that no wires are broken, you will most likely need to replace.
As the problem in that case relates to a damaged circuit board or chip.
Article by Slam, Last Updated June 2004