I use a Zebra GK420D to print our shipping labels and have use the same 2 printers for years. Monday it printed 2 labels and then on the 3rd it stopped in the middle of the barcode. When I flip the label 180 degrees it prints the top 80% and then stops in the middle of the barcode. Nothing has changed. Have tried different computers and reinstalling the printers. All of the paper size and print setting are correct. Any help would be appreciated.