I have a bunn coffee grinder that keeps on jamming up everytime you put coffee beans in it. I took the front part off to clean it out every time it jams,but it keeps on doing the same thing. The model bunn i have is g3hd,red

It sounds as though your grind is out of adjustment. The grinder is probably set too fine. I have not worked on a G3 grinder but I would think it is like the Bunn G2. On the front knob you will find 2 small set screws and one larger adjustment screw (in the middle of the knob)
1. Set the selector knob to finest setting (Espresso or Turkish)
2. Loosen the 2 set screws about 2 turns.
3. Activate the start switch (you must activate the "bag switch" behind the chute)
4. With the grinder running, SLOWLY turn the center screw clockwise only until you hear a very slight whirring sound (this is the burrs touching).
5. Then, back off the center screw counter-clockwise about 1/8 of a turn, shut off grinder and re-tighten the set screws.
Check the grind in the "drip" setting by running a few beans through... the grounds should be about the consistency of sand. You should get a better flow through the machine with the grind adjusted properly. You may want to check the cleanliness of the hopper in the top... I have seen these dirty enough to impede the falling of the beans to the grinder.
Also, whenever you remove (for cleaning) the 2 larger screws that hold on the front "plate", be sure to put them back in evenly... kind of like one would with a wheel on a car- Finger-tight then slightly tighten each on a little at a time (back and forth) until tight.
Hope this helps.