The pad on the print hammer has disintegrated and the
underlying metal
has been pounding on the print cylinder. This has caused some of the
letters images to be deformed so that only the top half of the letter
prints. A new print cylinder would be virtually impossible to fabricate,
so I need to find a new or used one.
With the new available it may not be worth the trouble but as long as the
damage isn't too deep you can get it to print acceptably by filing the
letters flat again, try printing and file again on the part of the letter
that prints darkest until you get reasonably even printing.