Hello everyone.
First-time visitor, first time typewriter-er
Recently came across a 70s-era Smith-Corona Galaxie Deluxe belonging to the girlfriend's mother from way back when.

I started checking how it works and noticed the apostrophe key jammed and was the only key to not move the carriage. Tried cleaning the type bars as per standard tutorials but that did not help, and opening the underside just shows a bewildering amount of springs and gears.

But I did find that the little spring-actioned wheel highlighted below (site is not allowing me to post images immediately, so I am posting the link), and the surrounding levers and gears, do not move when the key is pressed. That, I suppose, is why the carriage is not moving- something in between the type bar and this right here is jammed or out of place.. Because the back is solid, I can't see any further than this, and I don't want to go poking around and disassembling without any more advice.

Does anybody have any idea what's going on, and if there's anything I myself can do about it?
And yes, I know the underside is dirty...it hasn't been touched in 40 years! I'm a bit concerned about cleaning it, because I don't know what I'm allowed scrubbing and if there are specific areas on the underside I should re-oil after.

Cheers!
M

imgur.com/90indgX