I used WD-40 on my '69 Fleetwood's electric antenna. If I retracted it ALL the way, it didn't want to go back up.

A few squirts down the tube seemed to do the trick. Of course all the parts are metal on this old boat, so perhaps graphite or silcone grease is better when plastic is involved. I have some lithium grease, but that stuff attracts too much crud -- leave that for the door/trunk hinges.