I don't know that ZAQ2 means anything, but if you wanted to use any of these particular keys on this typewriter you were out of luck, because the Z, A, Q, and 2 keys didn't work.
We didn't have much in the way of nice things when I was growing up, but we did have a really nice typewriter. It was a Royal KMM, and my mother took care of it like it was the finest thing in the world. When it wasn't being used, it sat underneath a cover she had made for it. This typewriter had been manufactured in the 1940's, but even though it had been around a while, it always looked and functioned like new. The Royal KMM model was the same typewriter model used by Pear Buck, Tennessee Williams, Rod Serling, and several other famous writers.
I don't know what ever became of that old typewriter (I think my Dad must have sold it in a garage sale), but for a long time I've kept my eye out for one. A few weeks ago I ran across this one at a flea market, and just had to take it home.
My flea market find had a few problems: (1) the A, Q, 2, and Z keys were frozen -- wouldn't move at all; (2) a link between the Z key key lever and typebar was missing; (3) the platen clutch wouldn't engage (meaning the platen wouldn't index when the carriage was returned); (4) someone had put some sort of shiny, oily liquid on the platen (to make it look shiny & oily looking, I suppose); (5) the ribbon was shot; (6) the bell didn't "ding,"; (7) in some places the paint was chipped off; (8) the margin release didn't work; and (9) the whole unit was filthy.
Other than that it was fine......
Step 1: What you never want to do to a typewriter
Secondly, I should issue a word of caution. The one thing you never want to do to an old typewriter is fully disassemble it. Old desktop typewriters have somewhere around 3,000 - 3,500 individual parts, many of which look almost the same, but have subtle differences between them. The photo shown is of a more modern typewriter, which doesn't have nearly as many parts as these old one's, but it still has an impressive number.
The best way to destroy an old typewriter is to take it apart, because there is a very slim chance you will ever get it back into working condition. You only want to disassemble the parts that you absolutely have to in order to fix it. Seriously......