HP-41 HP82143A printer repair.

[AndiGer]

I saw that kind of printer arrangement in an HP-82162A only.
My guess: the clear something LHS of the encoder is the foto transistor that does the same job as the one that is on the RHS in the picture taken from the net.
But I don‘t know how the home position is detected on yours. Nor do I know why it prints fine when open. Has to do with light I guess …
Andi