Platen removal
Removing the platen from a late-model Underwood:
1) Collect your patient. This is Norma Jean, my 1960s era Underwood Touchmaster, an office machine. The platen was meant to be removable for ease of cleaning.
2) Either end of the platen is held down by panels that open like the hood of a car: they are hinged and on springs. On the Underwood, these can be lifted up with a little pressure. You should move the paper bail out of the way, and note that the lever that ratchets the line forward may get in the way.
3) One the right side of the platen, the Underwood has a small metal peg that fits into a groove near the knob, and a similar setup on the left, probably to ensure that the platen was inserted properly. With both panels open, this is a good time to look carefully at how it's seated, so you can put it back.
4) The platen just lifts out. Tah dah! I feel like a Repair God now.
For more info, see the excellent brochure on typewriter care located on this blog post.