1403 prior to 1403N1 used a chain. Plastic band with imbedded type slugs. Not user
modifiable. The thing that held it in the printer was user replaceable. The N1 used a 1416
train cartridge. Also could be swapped by the operator. It had a gate that could be opened
to remove/replace a slug. Looks like a CE would have to do it.
https://tangiblemediacollection.com/_images/typewriter-font/ibm-printer-cha…
The CHM 1403s use chain devices. They are paranoid about what they print in case they
break one. The plastic is 50+ years old. No OEM replacements around.