I found it! But this was something. After first search I found very little information about this device online. Some sites tricked me that they have manual available, but they were lying, playing dirty tricks with person in need. And this this site told me, that I can buy the manual for 2.32 USD. No way! I can recognize hoax when I see one.

Unless... I don't have any other option. There was no sign of manual. Maybe I could live without it, but this plotter has two rows of 8 switches to set operating parameters. And of course they are not signed. OK, I can risk loosing 2.32 USD, especially that there was a PayPal payment available, so no risk with sending card number oversees. So I used 10 minutes mail to create an account and made a payment. And you know what? I didn't bought operating manual, I got the maintenance manual. Yes! Now I know how to set these switches and repair what may not work. This is way better than I could expect.