I did not want to highjack your thread mersiepoo, since you were asking for advice. Seramas can you give us.....that don't know about tube feeding some more general information on tube feeding sick hens/baby chicks?
I use the tubers that are used for parrots. Also use the feed mixtures that they feed new hatched parrots, it is full of fruits and vegetables and the protein level in the area of 18-19% which is ideal for a sick chick/hen/roo.
The Large Syringe hooks up to a flexible tube the is gently pushed down the throat of the chick. When holding the beak open you will see that there is a strange hole in the back of the mouth/opening to the throat. If you watch it it will open and close. Do not put the tube into that opening for it will go into the lungs-a definite no-no! Push the tube down the back opening. You can feel it in the crop if it is in the proper place. When your sure it is in the crop you then push the plunger down on the syringe to force the food into the crop. Do not over fill either. For it may cause the chick to regurgitate and possibly breath some into the lungs.
For larger birds have several syringes filled with the needed food. This way you only unscrew the empty syringe from the tube and screw the full one back onto the tube without taking the tube out of the bird until you are finished feeding.
Practice on an healthy one before you have a sick bird to deal with. A healthy one will react when you do it wrong. And the practice will may it easier when you have a sick one to deal with, so much easier when you know what to expect.