Green/yellow is usually center tap for the 6.3V filament winding. You can check it with your meter to the outside windings for verification.
Are you measuring across the 5V winding (wire to wire), or to ground or something else for checking the rectifier filament winding? Is the transformer original? Maybe someone swapped transfomers and the new one did not have a 5V winding? That would explain why they might nix the rectifier tube.