If your not getting a decent hit either the weed is a bit damp, or you rolled it too tight, or you have a bud clot somewhere in the joint.

So... make sure it is dry, cut it up well, and remove all stems, and don't roll it real tight. Scrap the machine, learn to hand roll. Machines are for sissys.

Finally remember to pass the damn joint. Most time the joint goes out is because someone is yattering away and clean forgets to pass it. That person may need proding once in a while. Yelling at him/her to pass it may be required.