Pat, I have two different versions of this "fish line" tracker system
(which in my opinion works very well when in good condition), so I have
stuff to reference to "in hand."

As far as I know there is no "centering disk" as you describe.  Instead,
the shaft that the "paddle board" is on has a narrowed end (the shaft
is turned down to a smaller diameter, or it has a collar pressed on it
leaving a short length of the shaft protruding).  This small end fits
inside the hole of the two brass pieces in the drum and the spring goes
under them.  This holds the shaft centered in the drum, and pushes the
paddle shaft away from the drum.

The paddle is pinned to the shaft so it can move ("see-saw" on the
shaft), this allows for any misalignment of the shaft to the drum's
rim.  The other end of the shaft fits on a lever that is fixed at one
end, and has a bar at the other end that is fastened to the two rods
going to the roll edge feelers.  The interaction between these feelers
presses the paddle against the drum, or releases it.

A string is tied to the shaft, and it is wound and unwound by this
action.  The other end of the string is tied to a lever that moves the
roll back and forth--this lever is spring loaded to keep the string
under tension.

By the way, I use a heavy fish line for the string, or sometimes
upholstery sewing thread (#16 left twist).

Gee, is this clear as mud?  If you need more clarification and if you
want to send me pictures (but reduce them in size -- I'm on dial-up
service!), I can send you some back.

Good luck!

David Dewey
djdewey@cncnet.com.geentroep [delete ".geentroep" to reply]