Open the back door of the machine.
The filter that is smallest and mounted to a aluminum bracket is the fuel filter. it should have a bleed screw on top or just loosen the filter.
There in a inline primer bulb (like a outboard motor uses) in the fuel line (below the engine) prime it a few times until the fuel come out the filter or bleed screw.
It should fire up without too much cranking from this point.
It kinda depends on what it is, a 743 has as ken said, a hand primer. You need to loosen a valve at the injector pump to get fuel moving though. If its a 731 you need to crack a bleed screw and pump the lift pump priming lever. Later model machines will have the same setup as the 743, loosen the valve on the injector pump to get fuel to flow back to the fuel tank.
Make sure you re-tighten and bleed devices, i made this mistake once, the engine would start then just die, i wasn't sure what was going on at first, then it hit me.