I have a number of Lauter-related information and diagrams at the Player-Care web site, see:
Front view, tracker device
http://www.player-care.com/gifs/lautback.gif Back view, tracker device
http://www.player-care.com/lauter.html General tubing diagram
http://www.player-care.com/a_sign.html Accessing the piano action
As for the lever inside of the spool box that's on the right side, above the slotted spindle, the lever in my Lauter was designed to lock the spindle in place. As to why Lauter decided to incorporate such a function, the only thing I can figure is that it prevents the unit from being used if the person attempting to use it (a) wasn't aware of the levers existence or (b) was too small/short to reach the lever.
Now I'm not saying Lauter purposely installed a device that made it difficult for youngsters or inexperienced users from using the player, but I've never been able to come up with any logical reason for a "spindle lock".
John A. Tuttle
Date: Fri, 10 Aug 2001 07:45:01 -0400