Hello Mamagus,
You lucky cake. What a fantastic machine. Yes, it's definitely a 128K, manufactured in Scotland, and it's so similar to mine. Click on this link
http://www.quiltingboard.com/t-130994-11.htm Looking at the serial numbers, yours came off the production line 4851 machines after mine.
If you need help with threading, adjusting the tension or oiling and cleaning, watch my Youtube videos. Go to my profile and you will find the link there.
And don't even think of putting a motor on it, otherwise I will come straight round your place and kidnap the machine in the interests of its own safety. Distance no object.