In the Videojet manual it says, that after the 5 first digits of a zip, a “-“ should come, that is, 12345, 12345-6789, or 12345-678901. But I would try also without “-“. The Postnet does not really contain dashes. They probably filter it anyway. The length is “0” for as long as it is, or you can also set it to the # of characters (important when printing backwards).
Below you see what is sent to the inkjet.
[1B, 85, 08] is USPS on, the number [1B, 85, 09] is USPS off