Unblocking a hen's crop

Ever had to unblock a blocked hen's crop? I guess this is something few would ever need to do but we had to do precisely this recently. The crop is a muscular bag at the base of the neck. It holds the food the hen eats through the day and in the evening, the contents of the crop are then passed into the digestive system. Sometimes they become blocked, a problem that tends to be caused by eating long, stringy material such as grass. To clear the block, the crop needs to be massaged a few times to break up the clump of food. If this doesn't work, the hen has to be turned upside down and made to regurgitate the contents of the crop. Fortunately, we didn't have to do that in this instance.