Once files successfully make it out of Revit and into the printer queue, troubleshooting is on the printer side (that can be a good thing and a bad thing). I'd recommend heading over the manufacturer website for your printer and seeing if they have any suggestions.
Some things you can try if you're looking for some immediate ideas:
- Send one file at a time. I've seen printers get rather overloaded at times since they too have memory like a computer. 14 Revit files could be a bit much.
- Print to PDF first (try CutePDF, BlueBeam) and then print the PDF to actual paper. Sometimes it does the trick.