A few days ago, I picked up an Underwood 478, which looks just like the Underwood 660 in post 49 except for black segment cover and platen knobs. Black case. So how many variants of the Lettera 36 were made with the Underwood badge? Doesn't seem like this is a well-known model; only one example on the Typewriter Database (posted by Richard Polt as it happens).

I only had a chance to fire it up today; it's been sitting a long time so some of the keys have been a little slow to "wake up." The C/c key remains dead though. I'm wondering how to get into the linkages to see what's going on -- whether cleaning is all that's needed or if it's something more serious. Any advice on what it could be, or how to get into the innards, is most welcome.

Thanks! Right, the ribbon cover comes right off. And the keyboard cover lifts off as well, so that's a little different. It looks to me like there are four screws on the bottom that would have to be removed, but I will need to check that out further.

I'm particularly interested to see what the key linkages are -- is there something mechanical causing the C key to not function, or if it's an electrical thing. If the latter, that's maybe a problem since I would be very unsure of how to proceed.