Adding machines are used by many businesses to add up important numbers and have a record of the transaction. The ribbon is essential in adding machines; without it there is no way to verify that the information was accurately calculated. Knowing how to change the ribbon becomes a necessity because they don't last forever. Each adding machine is a little different, but the basic process for changng the ribbon is the same.
Remove the printer cover. The cover is usually on the top of the printer near where the paper feeds through. Remove it by pressing down on a section of the cover and sliding it back.
Remove the old ribbon spools. Some machines will have a lever to release the ribbon and spools; others will allow you to pull the spools straight up, taking the ribbon as well.
Insert the new spools into the machine. Double-check the alignment specific to your adding machine; most of them will require the black ink to be on top and the red ink (if available) to be on the bottom. Also make sure that you do not install the spool backward; your machine will perform as if the ribbon is at the end if you do. Make sure that the ribbon is securely in place.
Replace the printer cover, sliding it back into place. Run a few calculations on the adding machine to make sure that everything is working properly before resuming your normal work.