Maybe either the solvent in the carb cleaner or the plastic in the valve has changed. Chlorinated hydrocarbons have been banned in a lot of cases and other solvents substituted for them in carb and brake cleaners. Maybe the can label can tell you what solvent it is that is causing problems and try aother solvent class. Or, maybe "cook" the parts in antifreeze in a crock pot?????? I have not tried to AF so try it with a bad valve first.

Good luck.

Sincerely, SPACEWORM, Saito Club #635