We have inherited what we believe to be a Wurlitzer 105 band organ.  I know it ran well 10-20 years ago, but is now missing many notes.  I am a mechanical engineer but am still struggling to understand how the vacuum and pneumatic circuits work.

How does vacuum get to the underside of the pouch in the block valves?  There is a bleed hole, but it appears to dead end into the gasket on the backside of the block.

Do paper rolls get porous with age? We have about a dozen -- some seem to work better (play more notes) than others. Is that because they have a lighter note density, or because the paper is less porous?

I have searched these forums for a trouble shooting guide, but have not yet found one.

Any help is appreciated. We did not expect to become foster parents for this thing, but are fascinated by it.

David Miller
doctorflywheel@gmail.com.geentroep [delete ".geentroep" to reply]

 [ "Do paper rolls get porous with age?" Perhaps -- but a pneumatic
 [ player system most certainly becomes porous with age. A stethoscope
 [ and a manometer will help you to locate some of the external vacuum
 [ and wind leaks. See the MMDigest articles at
 [ https://www.mmdigest.com/archives/KWIC/S/stethoscope.html 
 [ https://www.mmdigest.com/archives/KWIC/M/manometer.html 
 [ https://www.mmdigest.com/Tech/vanceGage.html 
 [ -- Robbie