How could a specific typewriter be tracked from a typed document?
However, looking at a document, you may be able to tell the make and model of the typewriter, due to different typefaces and known mechanical differences across the make/model. That, coupled with a location or list of suspects, would allow you to examine specific typewriters. You may be able to determine a letter was written from a -given- typewriter, as machining differences in the keys, and differences in wear and tear over time can lead to minute differences in how the ink adheres. If you also have a letter written by a specific suspect, the variation in typing (how hard they hit the keys, common typing mistakes, etc) can lead to greater certainty of the author.
Actually, yes. Typewriters, especially well-used ones develop their own quirks. The "e" is a little higher or lower. The "o" gets a little filled with ink. It's mechanical, so parts wear, things get a bit off, and with enough use, each typewriter develops its own fingerprint.
It's been a thing in mystery novels at least back to the 1920's.
What -you- are describing, is "Was this particular document written on this particular typewriter", which is possible by comparing it against a document you know to have been written by that typewriter, and which I detail in my answer which you didn't fully read ("That (...) would allow you to examine specific typewriters. You may be able to determine a letter was written from a -given- typewriter").
This is identical to ballistics; finding a fired bullet does not tell you the specific gun that fired it (but may tell you the model/make; certainly, it will tell you the type of ammunition it takes). But if you have a bullet of known provenance (i.e., one you fired from a suspect's gun), you can tell if the markings left on the bullets match.
It's the reason why ransom notes from old movies are made of letters cut out from different magazines and newspapers. No handwriting, and no typewriter.
Did you know that US Secret service has samples of ink from various ball point pens? (https://www.12news.com/article/news/nation-world/look-inside...)
It's similar to e.g. identifying specific guns by the markings left by imperfections of the barrel, you'd also take sample shots which can then be matched to the specific gun.