From the pictures you've posted, it seems to be in good shape. A lot(!) of scratches on the soundboard behind the bridge, but no obvious problems.
I can't be sure, but the soundboard (lighter wood on the top) seems to be solid timber all the way through - meaning it's possibly one-piece, better than the thin plywood like you get on more modern cheap guitars.
It has a zero-fret which is unusual (though note, this is not a bad thing); I've read this is often seen on older European-made guitars though I'm not an authority on that. (Some people will tell you a zero fret is a bad thing - but that's a myth, they're fine if the setup is OK.)
It may be possible to replace the tuner - they're usually supplied as two plates with three on each, but the size and the distance between tuner shafts and between fixing screws sometimes varies, so if replacing it you should check the tuners against the guitar when buying...
So: I wouldn't know about any value to collectors (I'm not one) but if it plays OK I would certainly keep it.
One thing I'd look out for: it appears to be a classical-style guitar, but it looks like it's wearing steel strings. These probably have higher tension than the more usual nylon-style strings fitted to classicals. So if you tune this up or put new steel strings on, beware of putting too much tension on the bridge and soundboard. (I'd recommend classical guitar strings if you want to replace the ones it's got.)