As ImageWriters and wide-carriage ImageWriters become older, the lubricants
used on the carriage rails tend to dry up and prevent the carriage assembly
from moving freely during printing. This can lead to unacceptable horizontal
print registration: columns of characters don't line up properly from one
line to the next, and appear to be shifted anywhere from one dot to half a
character.
When this happens, thoroughly clean both guide rails with a degreasing
solution and lint free cloth, then lubricate them. Clean the rail all the
way around, not just the surface area visible from the top.