steam system air lock on return

Stan_6

I have a steam boiler that I have been having a problem with one area of the house. The steam only travels half way down that branch and stops. I found that the return line from that branch is very hot. The pitch of the supply and return are correct. I have changed the steam vents and the main on that branch. I have found out that when I drain the return line the steam will travel all the way through that branch of that area. Please help.

thfurnitureguy_4

drain water from the return? can you snap a picture? where you vent is at this branch.