[OldRestorer]

Hmmmm,

 I have a 6-D-510 but for the life of me I cant tell a difference...

I think it is the same and I literally just changed mine.
Does yours have 2 springs soldered onto the wheel?


If so then it is an easy string.
one end of the string goes on one end of the string. run it strait down under the chassis and wrap it 2 times clockwise.
The up through the oval hole to the other side if the wheel. Tie it fairly tight so the spring has opened a bit.
Here is the string guide that resembles it most.