how can I fix my Bell-Howell 1615 projector?

My projector is a Bell-Howell 1615 duel 8mm with auto load. The problem is that after I ran film through it two or three times it stopped feeding. When the film first starts into the feeder you can hear it trying to catch but it will not feed. Also I installed a new bulb,which works, but I could not get it to project onto the screen. Projectors are new to me so I don't know if I am doing something wrong.Do I have to be running film through it for it to project a light?