It was "Duco Plastic Cement".  Now I use "Sigment Model Airplane Glue".
The valves were made by the same manufacturer that made tail light
covers for automobiles, hence the amber valves, red valves, and the
clear plastic valves.

Originally they had a bleed hole just drilled into the plastic.  They
had problems with the valves so they put in real brass bleeds.  They
still had problems with the valves because of the sponge neoprene but
no one would believe that was a problem because the valves were so
airtight.  Leather would have worked better because it can actually
slide or slip into place.

Don Teach - Shreveport Music Co.
Shreveport, Louisiana