Hi Vernit

First things first, welcome to the forum and the world of typewriters. I'm sure we'll be able to help you sort out your problem, just need a little more information so we know what we're dealing with here. Do you know now roughly how old your SC Sterling is? Smith-Corona had a few different line advance mechanisms through the production years of the Sterling. If you can find the serial number, that would be a great help. The serial number is stamped on the frame, just in front of a ribbon spool. The early models had the serial number on the right side while the later models had it on the left, see pictures.





I realize the second picture is the serial number of a Smith-Corona Clipper, but the Sterling of the same era had the S/N in the same location. All the best,

Sky

Hi Again Vernit

The serial number dates your machine to 1963 or possibly very early 1964, just a few years after Smith-Corona became Smith-Corona-Marchand (SCM). Here are a few suggestions and a few questions to see if we can get to the root of your problem.

Q-1. Can you turn the platen with the right platen knob? Yes / No.
Q-2. Can you turn the platen with the left platen knob? Yes / No.

If no to both, we likely have a deeper problem. Pull the line finder release button out from center of the left platen knob.


This will release the drive from the platen and the platen should turn freely. If the platen still won't turn, pull the paper release lever forward to disengage the feed rollers (I've seen feed rollers get stuck to the platen before).


If the platen still won't turn, you'll have to lift the platen out of the carriage, we'll get to that in the next post if necessary.

If the platen does turn with the line finder release pulled out, disengage the platen indexing detent by pulling this little lever forward.


The platen drive should now rotate freely. If it doesn't, we'll have to dig a little deeper. Please let us know what you find,

Sky

Is the carriage return lever pivoting about 15 or so degrees when you pull on it to move the carriage? Looking at the machine as if to type, hold the right side of the carriage steady and push the carriage return lever as if you are moving it to type another line. It should move easily and this is what should be engaging the platen gear to turn it. If the carriage return lever doesn't pivot, that's probably where your problem is. 

If you rotate the platen when the line finder release button is pushed IN to the left hand platen knob, does the toothed wheel move? If not, you will have to remove the platen and have it repaired. Could be that little spring in there which wraps around the core of the platen and releases it for the line finder. Unfortunately, removing the platen from the Sterling is a couple more steps complicated than the Silent or the Silent Super, those have a really quick system to disengage the whole platen for cleaning. It allows access to the rollers underneath as well. The Sterling needs to have a few screws removed here and there, as well as the carriage side plates and the knobs themselves. If it does rotate, and you feel the notches, then that side of the carriage probably needs a very good cleaning. This is one of the places in the typewriter that usually has polymerized lube which has turned very hard, binding everything up. My 1949 SC Silent was like this when it arrived. Most of the machine was very sluggish. It just needed a very good cleaning. A SC Skyriter which just arrived is even worse. Typebars move like I am filming them at 1000 frames/second, all slow motion. It would probably not hurt to move the carriage all the way left, hang that side over a bucket and just flush it with mineral spirits or naptha. 
I have a Super 5 series Sterling which I need to clean so I can help you work through this side-by side if necessary. I need more distractions from completing my thesis.
Phil Forrest

Hello. Looking at the carriage return lever, it doesn't travel as far as it does in Sky's picture, and flicking the line space selector does nothing. That little hook connecting to the gear supposed to turn the platen just gets stuck. All springs are there. Going to try the wash soon - will get back to two helpful people on the internet.