Is this the model you're talking about?

Guess I'll Try wrote:

1I was recently given this typewriter, and what a unique machine it is.  Searching the internet, I found pictures that match the one I have.  Earlier machines have glass top keys, this has black plastic, and plastic spool tops.  The strange thing is, to me that is, the key bars are doubled, that is two arms to a slug.  And it is almose noiseless!  At first the slugs did not seem to hit the platen, but after reinking the ribbon with stamp-pad ink, I saw they did. 

I read somewhere that the distance of the platen from the striking point could be adjusted, and that this is often mistaken for touch control. Try fiddling with that lever (on the front panel) to see if it makes a difference. If we are talking about the same machine, it uses two characters per slug because the "noiseless" action makes the slugs thicker and therefore to fit all the letters and figures they had to combine some on the same slug. It's a genius design, really.

Yes, it is portable--sorry for the delay, I have just submitted another article on the same machine.  The typewriter looks like the picture you posted, but with crinkle finish, and only the Underwood Noiseless 77 printed on the front bar below the keyboard.  I haven't checked the "touch control" to see if that adjust's the platen, but will.   

That's a beautiful piece