I'm working on a Model S Aeolian Orchestrelle. The valve chamber
is covered with an interesting 1/8" plywood with three layers.
The inner layer is walnut, the outer layer is cherry, and the middle
layer looks like a thin aluminum or lead foil.

Aeolian used a rubbery glue to hold all this together. This glue is
failing but the veneers have no holes or splits. I assume they used
this stuff for air-tightness. I'm wondering if I should leave it
alone or replace it.

Philip Jamison