Hi Les,  there are no replacement rubber diaphragms for the plastic
bellows.  Even if one could rebuild them the air supply and pressure
is not sufficient for the proper bird song operation.  They were
cheap in the first place.

We rebuild the cage with a wood whistle and zephyr-skin bellows and
require the entire cage to complete the operation.  If interested
call me at 1-888-711-4646 or 1-310-514-3038

Tony Ciuffini
San Pedro, California