Lathem platen and ribbon combination
If the clock is printing poorly, tip up the clock movement and pull the ribbon aside.  If you see a crumbling piece of gray plastic, then that is the problem.  It's easy to replace, we can send you a link on how to do it.  
You will need a ribbon, a platen, and 15 minutes of your time (probably less).  These are the Lathem parts that you need to fix this problem.

 



 
Website Search Terms:  lathem platen, lathem ribbon, lathem service, lathem repairs, lathem parts