I have been playing with it a bit, it is a really neat gadget. It does have a working bubble, and the sliding parts are nice and tight but not siezed. (In fact, it is cut to such close tolorances, that it will not assemble unless you put it together *exactly* flat)
The scale, unfortunately got a small case rust frost, but it partly cleaned up with early efforts, should clean up ok without losing the scribed lines.
The thumbscrew is going to be interesting to find tho, I almost needed 2 of them, apparently it has a spring inside it, luckly, it landed on the table ;P