TV cables getting stuck in conduit after mounting TV on fireplace
Vacuum a string through the conduit. Literally put a vacuum cleaner sucking on one end and feed string in the other until it comes out.

Then PULL the wires (all of them, at once) into the conduit with the string. That works easier if you make the front end of the cable bundle somewhat smooth as you attach the string, generally by wrapping tape to cover the connectors, etc that will want to catch. You can have your helper push a little as you pull.

Stagger the connectors (put one behind the first one, and the next one behind that) so they don't make a big fat lump right at the end.