Adding machine problems. I cannot seem to put the ink back into a Royal 210PD adding machine (very

Question

I cannot seem to put the ink back into a Royal 210PD adding machine (very old, I know)

please helpcanon p10150 adding machine - very old but still works great! I need to change the ink roller (after 15 years) and can't figure out how to open the mechanism.

We recently acquired an old Royal EZ Vue adding machine. We stuck the paper roll straight into the slot in the back but we can't get it to grab and pull the paper through. We took the cover off and saw that the roller mechanism is working/turning as buttons are pushed. We just can't get the paper to it. Any suggestions?