Hi Jonathon,
Is anything hydraulically working? If not, more than likely it will need a new hydraulic pump. I believe, this unit has auto-feed. It could also be an auto-feed tach as well. Usually the feed wheels start turning once the auto-feed tach hits the low RPM settings in the tach. There is a button you can hit on the tach that will shut off the auto-feed. When you shut them off, they will automatically start turning. You will then have to work the bar. I don't know if it's a fuel chipper that has no bar. There are so many things that can effect the feed rollers.
Hope this helps!
Dave
Global Equipment Exporters
770-420-6400