From Keen On Keys.

The MP-1 is the world’s first and only portable keyboard with a music printer. It features 44 mid-sized keys, 8 note polyphony, 10 voices with sustain, 10 rhythms with variation, duet function, transposer and chord and melody memory. It sounds exactly the same as the PC-100 and PS-400 and was also released in 1982.

Support this channel and buy a song or album on Bandcamp: https://keenonkeys.bandcamp.com

0:00 Overview
4:34 A Look Inside
7:01 Repair
9:39 Cleaning
11:32 Ballpoint Pens
13:00 Print and Play
14:57 Memory Print
17:29 Paper Change
18:48 16th Notes
20:12 Sensitivity
21:33 Reproducing
23:09 Conclusion

New brass gears:
https://www.soigeneris.com/alps-printer-plotter-mechanism-pinion-gears

New pens:
https://www.evident-shop.de/en/diagnostics/plotter-pens/250/plotter-pen-set-of-4-pens-in-black
(They also sell the thermal paper I used in the video)

More information about repair and refilling the pens can be found here:
http://tandy.wiki/CGP-115

Magazine scans by: http://www.muzines.co.uk/

Listen to some tracks on Soundcloud:
https://soundcloud.com/user-229361059