The restoration of the pneumatic player units for this magnificent
instrument was done by Thomas Jansen of the Musikwerkstatt Monschau,
Germany.  This task of pneumatic brain surgery included replacing 4 km
(almost three miles) of lead tubing.

A number of fascinating photos of the organ and the components undergoing
restoration can be found at http://www.maesto.com/US/welteinstruments.html

Jurgen Goering - Piano Forte Supply
http://www.pianofortesupply.com/