When we rewired our mast, we found the wires had been wrapped in chucks of foam every 3- 5 feet before pulling them up the mast. While this made the wires quite, it did not make for easy replacement. The foam was old and rotting and got hung up on everything in the mast. The biggest issue took a while to figure out, there is a bolt all the way through the mast at the spreaders which blocked up the foam. In hind sight I should have figured that one out quick, but for some reason it did not register until I fought with the foam and wires for quite some time. I must admit also that I believe it was my wife who finnally came along and said "Looks like there's a bolt through here, could that be your problem?"
Also, I would advise pulling two messenger lines if you can, that way you will have a backup if something goes wrong and the first one gets goofed up.