You need a lot more than just a key, but don't despair. I've seen entire machines being parted out on eBay, so if you're lucky you'll come across someone who is selling those parts. I don't know where you live, but you might also want to contact any typewriter repair shops that might still exist in your area - or in other cities for that matter. Some members here have lucked with sourcing parts from such places.

Essentially all of the parts from the key itself backward (I can't tell from the photo). Just use the neighbouring key arm as a reference and follow it to see what else might be gone, look for any missing springs, or damage past the point the missing arm was snapped off. Photos will help when contacting typewriter shops. I really hope you manage to save this machine; the QDL is an exceptional typewriter, but its practical use is pretty limited without a working letter M.

If it's the one I've heard of then you'll be in good hands. Oh, and good luck!

TypicalType wrote:

Looks like there is a shop in Cambridge. Going to lug it there on Tuesday for them to inspect in person. Wish me luck!

Are you talking about Cambridge Typewriter in Cambrige, MA or a different Cambridge? Congrats on your new typewriter either way!!