I'm working on a Seybold player and the pot metal tracker cam is
broken.  It is a U-type with the connection arm is 90 degrees to
the cam which the connecting rod passes through the transmission.
Dimensions: 22 mm wide, connecting arm height 40 mm, cam arm length
42 mm.

Hopefully, something like this floating around which will save me
the trouble of making one.  JPEG photo available.

Best Regards,
Jon Page,   piano technician
Harwich Port, Cape Cod, Mass.