Although this part of The Quad ESL is permanently closed, you can still obtain ALL repair materials and electronics from ER AUDIO.   

See embedded web page below from ER Audio.

All the diaphragm films including the original Melinex.
Coatings.
EHT supplies.
Dust cover materials.

As usual, you may use information from this site free of charge to rebuild your Quads, and the materials are still readily available from ER Audio.