There is no printer ribbon. it uses thermal paper.
The biggest problem
with the printer is that the paper feed mechanism wears out and it can't be
fixed.
The last HP97 I got had this problem. The printer can be taken apart
(there's an exploded diagram in the service manual), and the roller
removed. It's got those well-known silicone rubber tyres on the ends. I
was thinking of cutting them off and using silicone rubber tubing to
replace them. But before I went to all that trouble, I tried rubbing them
will 1000 grit wet-n-dry paper, just to take the glaze off them. Worked
fine... When it goes again, I'll probably have to renew them, though.
-tony