Recently purchased 1989 MC18, everything wonderful but speedo doesn't
work. Former owner put new cable on with no luck. But when I look inside
on driving end of business(ie not the end where it goes onto speedo), the cable end is squarish and does not reach
far enough to touch a round hole being somehow driven off front sprocket.
I could not see well enough to tell if that round hole was threaded or not.

I look at Tyga website and it lists the same pattern speedo cable as
fitting 18/21/28. Is that truly correct? If that is, then I suspect I am
missing some piece inside that interfaces between the cable end and the
drive.

Any ideas?

Thanks in advance!
Maxine