As above, the vac and string can work well.
Also, if you have a mig welder, use it to feed the wire down conduit ( welding wire acts as a good draw wire) make sure you bend the end over before feeding it down and do it with the conduit in a straight line.
Also, if you have a mig welder, use it to feed the wire down conduit ( welding wire acts as a good draw wire) make sure you bend the end over before feeding it down and do it with the conduit in a straight line.