HP 97 printhead not moving full distance

[Chr Yoko]

I completely put mine appart recently and it is a pretty simple mechanism.

Gears cascading from the motor down to the print head screw shaft must be in good shape with their teeth still ok : this is what moves the head left-right.

There is a black plastic drum on the paper advance shaft with a groove into witch a pin is attached to the print head is sliding , make sure it is properly engaged : this is that movement that rolls the paper up after a carriage return (ie when the head is coming all the way back from the right to the left, it turns the paper shaft by the equivalent of a printing line).

Motor => Pinions/gears => Screw => Head motion L/R => Paper-Shaft rotation after the head carriage return
or
Motor rotation => Head Translation => Paper shaft rotation