[ Steve Marx wrote in 081028 MMDigest:

> I'm seeking a few sets of player tracker fingers, the ones
> that touch the edge of the paper roll to keep it tracking
> (some people call them ears).  Aeolians are preferred, would
> consider others such as Amphion, Hardman & Peck, etc.

Aeolian tracker ear assemblies of the common paired type are often
difficult to mount in other makes because they require a specific
distance between the edge of the roll and the sides of the spoolbox.
In later instruments they are mounted "upside-down", bringing the
contact point just above the tracker bar and thus closer to the source
of tracking error.

Amphion fingers of the bent wire type are not recommended because they
confine pressure to a very small area of the paper edges, putting great
stress on the paper at the contact point.  They do, however, have the
advantage of weighted valves, so there is no problem of determining
and adjusting spring tension.  This advantage does not offset the
relatively small diameter of the wire and paper contact being made
below the tracker bar.

Here in the USA, nearly all Hardman-Peck-built player actions have
a single ear bearing against the left edge of the roll -- the worst
type of tracking system ever devised.  The right-hand ear assembly
found only on the very late actions with a double pneumatic is a
mirror-image of the left.  It would be good if somebody started making
these up in matched pairs.  They're easy to install.

Unfortunately, none of the makes mentioned have any means of lifting
the ears away from the paper during reroll -- a highly desirable
feature.

Jeffrey R. Wood