First you need to figure out is this the job, the output device or the RIP hardware/software.
To test this I would recommend the following:
1. If this is the only job exhibiting the problem then it may be job related. Possibly resolution settings or incorrect (low resolution) images in the job itself causing the issue.
2. Does this problem show up in the ROAM or preview of the RIP? If it does then you have a setting in the RIP set incorrectly, you have an interpretation issue with the RIP interpretting the data or it is something with the job. If it does not show up in the ROAM but shows up on output then you may want to check your cabling and check to make sure the PCI card in the computer is seated correctly.
3. Always run a self test on the output device to make sure there is nothing wrong with the machine itself. If this is the only job exhibiting the problem then you do not have to do this step.
Good luck.