I would probably try taking a piece of flexable rubber hose and tape it to a (thicker guage) wire coat hanger. You can then bend the hose (and keep it in that shape) so as to enter the hole and curve down. You could even attach a strong piece of string near the opening of the hose (to the coat hanger) and then run that string out the hole as well, allowing you to adjust the angle of the bend (to drecrease the radius of the bend) of the coat-hanger to get the areas nearest the hole.
I'd rig this to a small wet-dry vac and try to vacuum the part out. I wouldn't give up!
I'd rig this to a small wet-dry vac and try to vacuum the part out. I wouldn't give up!