I'd just like to mention that I have completed the repair of a vintage 1976
HP9830B BASIC calculator and HP9866B printer. If you are interested in the
story, take a look here:
http://www.datormuseum.se/computers/hewlett-packard/hp9830
I also made a short video on it when it is running:
https://www.youtube.com/watch?v=WE8KJ4-UcFk
/Mattis