So: what is this piece I showed you yesterday?
It comes from an Underwood no. 5 and is called the line space disengaging cam. Found next to the left platen knob, it allows you to type temporarily between the horizontal lines of your typescript. In order to remove an Underwood platen, you have to remove this piece.
I'm currently working on a beautiful no. 5 made in 1929. I've gotten familiar enough with these typewriters that it took me only seven minutes to break it up into these parts:
The typebar rest on this machine has an inscription woven into it that you don't see every day:
"Underwood pad pat. in U.S. & all foreign countries. Patented & licensed only for insertion in Underwood typewriters. Made in U.S.A. by the patentees."
Would you like to know how to remove an Underwood carriage and platen? It's essential for good cleaning as well as for mechanical repairs, such as adjusting the ribbon throw. Here are the instructions, straight from holy writ, the 1945 Ames Typewriter Mechanical Training Manual. (You can download the whole thing on my website—see the bottom of this page.)
Can you spot the line space disengaging cam on one of these diagrams?
PS: Thanks to the Kalamazoo Typochondriacs for a fun visit by Skype today!