https://www.reddit.com/r/typewriters/comments/21zpri/what_you_should_know_before_cleaning_your/

Note the stated 33 year experience as typewriter repairman

Most typewriter shops did not use alcohol as it was ineffective and contained water. Industrial alcohols contained keytones and acetones that will melt plastic and remove paint.

Solvents for typewriters used in repair shops: - White mineral spirits with a squeeze bottle. (Sometimes also called Varsol, Stoddard's Formula, and possibly Inhibisol) - Naphtha (aka lighter fluid; used in Zippo lighters, and frequently seen in Europe). PB B'laster is essentially pressurized naphtha in a can. - Auto carb and brake cleaners, usually pressurized in a can. These usually have acetone in them and will melt plastic. Will remove WD-40 if accidentally used on a typewriter.

For cleaning typeslugs, one can use naphtha or mineral spirits with a brass bristle brush.

For platen cleaning try mineral spirits or fedron.

Only oil the carriage rails for the bearings or trucks.

(This is all colloquial advice, albeit with experience, so check specific facts about what certain products contain.)

Is it telling that a typewriter shop around since 1947 only has one segment pick?

Everyone mentioned most of the usual tricks, but one.

To get your sticky typewriter keys working again, while you're flushing out the segment with your solvent of choice (lacquer thinner, paint thinner, mineral spirits, alcohol, etc.), actually move the typebars using the keys or by other means. This will help to get them moving and allow the solvent and subsequently compressed air to help flush the oil, dust, hair, etc. out of your machine. You've already got a mechanical cleaning device of sorts (the typebar itself) inside the segment, so move it while you're flushing it out!

It may take a few repeated treatments/attempts to get it all clear for all the keys, but it's far easier than taking everything apart.

reply to u/nogaesallowed at https://www.reddit.com/r/typewriters/comments/1cp75ln/how_do_you_clean_a_1mm_gap/

People were recommending all sorts of ideas and solvents here, including folded card stock, tooth brushes, floss, toothpicks, interdental brushes, wood cuticle sticks, Swiss Army knife tweezers, microbrushes, and even an ultrasonic cleaner.

Royal Quiet De Luxe Typewriter Sticky Keys Segment Flush Clean by [[Phoenix Typewriter]]