Question edited for clarity, make and model (what it is).
Question moved to Smith Corona.
You have a stuck key, the one that is typing the same letter! It probably needs a good service as no one has used a portable typewriter for 30 - 35 years :>D
https://www.google.com/search?q=SL470+stuck+key
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Question edited for Clarity.
Almost certainly nowhere. Sears advertises 'parts', but only the ribbon and says they are obsolete and no replacements. The computer and computer printer has killed the typewriter market.
You might get a used one on eBay and strip it for spares.
https://www.google.com/search?q=smith+corona+se100+spare+parts
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How to Use a Smith Corona Typewriter
A Smith Corona typewriter can be either a manual or electric model. Whichever model you have, the typewriter works in basically the same way. If you are familiar with a computer keyboard, you can type on a typewriter as the keys are laid out exactly the same. Unlike a computer, typing mistakes are harder to correct and, unless you use carbon paper, you will only have one copy of any document you type. A Smith Corona typewriter can be either a manual or electric model. Whichever model you have, the typewriter works in basically the same way. If you are familiar with a computer keyboard, you can type on a typewriter as the keys are laid out exactly the same. Unlike a computer, typing mistakes are harder to correct and, unless you use carbon paper, you will only have one copy of any document you type.
Brand new? Contact the seller and/or manufacturer about the warranty. https://www.smithcorona.com/
Is this the machine? https://www.amazon.com/Smith-corona-Coronamatic-Portable-Electric-Typewriter/dp/B0112YFSFE
Anyway, if the keys type and the ink isn't showing, the problem seems to be with the ribbon. If it is not advancing, the keys hit the same spot repeatedly, no ink. If it is advancing, there may be a
control that modifies the striking power of the keys and that might be adjusted. If it is not a matter of striking power, perhaps the ribbon was not installed properly or simply was dried out. https://www.youtube.com/watch?v=CF0rskT16jQ
As to the space bar not working, that probably requires some disassembly. Here is a page describing the general problem: https://www.instructables.com/Easy-Spacebar-Repair/
Here is a page for disassembly: https://www.youtube.com/watch?v=UVLDvPdgebU
However, this could easily turn into a fiasco of the type where someone opens up a watch and thinks they can repair it. They don't have the tools nor the technical skills. That's reason enough to call the manufacturer for warranty info and/or support.
Most likely bad printwheel, spokes may be catching on the ribbon and not going to home position. Try a new wheel, and or make sure carrier is returning to home position every time. make with white out the top of the print wheel spoke at home position and make sure it always comes back to that spot when you turn machine on and off and on. This will tell you if the machine is starting in the same place every time.
