What have you had luck with getting from one end of the tube to the other? Need to go from the front to the back thru the tube. Big light on the front, switch at the back.
Use compressed air to blow a cotton string through the conduit. The air will scoot the string along then tie anything to the string and pull it through. For heavier things you may have to pull a wire with the sting in order to pull your other things if the string could break.