These typewriters are notorious for this problem, and it usually lies, believe it or not, with the ribbon advance mechanism.  If the ribbon isn't wound right, or if anything on the geartrain is stuck because of dirt, or if the mechanism that releases the drive gear from the spring drum is stuck, assuming that they began using a mechanism that prevents ribbon travel when the tabulator us used, you're going to have problems.  Of course, there are other causes, such as a sticky escapement wheel.  the escapement mechanism needs to be cleaned and well oiled as well, as the escapement wheel spins as the carriage is slid either to the right or left.  Also, the tracks need to be cleaned and oiled as well.  L. C. Smiths and Smith-Coronas (later) are fairly finicky about this.  When they're used fairly often and kept clean, they do all right, but once they're neglected and left to rust and get dirty, they develop serious issues because they're interdependent mechanically--a little like an IBM Selectric.

Thats great that you got the carriage off!

Anyways, To reattach the draw band, first, from the back of the typewriter, turn the spring drum 4 times to the left. Then, hook on the clip to the little nub on the drum. Then, there should be a little tab next to the serial number. Hook the other end of the draw band on that for now. Reattach the carriage using my steps, and then when your ready, hook that other end that was by the serial number onto the end of the carriage. It should be just enough force.

If I remember right, there should be either a tab or a screw under the carriage all the way at the end. You'll be able to find it, I just dont remember what it is.

I couldn't find that screw to save my tailbone.  But I did find a tiny tab on the left end of the carriage that isn't on the right and seems to have suffered stress over time (the paint is rubbed off) which indicates it served an actual use.  Perhaps that's the tab you're describing.  I'm giving up tonight.  I'm losing the light and just threw a cover over it.  It's been a bad machine so it's spending the night on the porch.  Also, had hell getting the carriage on and not knocking the lower ball retainer out of alignment.  Arrgh.  Is there an easy way to do that?  

Got the machine back together with no unidentified parts left over.  Whew.  Drawband is reattached, tension reset and typing / spacing action is now normal.  Unfortunately, I have something misaligned.  The margin bell has ceased working.  The carriage will not travel to extreme right and left ends of the platen.  It can be forced but then the whole carriage rocks, bucks upward and gets stuck.  Pushing it back into place leaves me at square one.  Have disassembled and reassembled several times but can;t how to resolve the issue.  Not sure if this is even connected but now the ribbon doesn't seem to advance when typing.  Arrrgh.