Don,
I did a 'how to' thread a while back on the re-laying of ribs. Yes there are spacers between the barrels that get tinned. All tinning is done with acid flux with the parts separate from one another. Getting solder to stick without acid flux is a problem. Once the tinning is done on all the parts, a thorough cleaning to remove the residual acid flux is necessary. Soap and water with a Scotchbrite pad and small wirebrush is what I used.
This link to Drew's site that captured my thread and some of Dewey McVicker's and Oscar Gaddy's ideas is a great reference.
http://www.picturetrail.com/sfx/album/view/18691676/297178486BTW, I used 60/40 tin/lead solder. A friend that does high-end conservator/restoration type of work for a living suggested going to 63/37 true eutectic solder for the lowest melting point, but I didn't find I needed it.