I've repaired successfully the card reader with new o-rings, but it seems it not always reads cards properly as it reports sometimes with "Error".

Walking through some threads here it turned out that the "pinch roller axle" might be the case. But I don't find this term in the HP-97 service manual on page 6-6 with all mechanical parts listed.

Is the roller axle item number "5" called "00065-20201 Roller" ?

The axle is called the "eccentric cam". Look closely and you'll see it's oval in cross section and has a flat screwdriver blade slot in the end to facilitate rotation. As you rotate this, it will apply varying pressure on the card as it's being pulled through the reader. The manual discusses the proper motor current you should seek while adjusting this cam. It's hard to do this by using just current measurements (at least I never quite get it right that way) but you can simply experiment with it to see if you get fewer errors.

I've also seen errors come up if the motor to gear coupling slips, there are poor contacts between the gold spring contacts (67) or if the contacts on top of the balls are not clean or out of adjustment.