If it isn't in working order, a forum search for Werra will find you details of a repairer in the UK (if it doesn't, PM me).
I've a green flat-top Werra 1 and a later Werra 3, both of which will take pictures far better than I can make them - sadly, not difficult! In common with most 2.8 Tessars, best when stopped down a couple of stops, but once you do that they are lovely and sharp, with good colour rendition.
First thing to test when it arrives is that both shutters are OK. Take the back off, and wind on whilst looking at the back - you should see the capping shutter blades reset. Peer through it and press the shutter release, check whether the shutters both open. If they do, put your eye to the back and wind on again - if you don't see light, but when you take your eye away the capping shutter blades have reset, then all well and good. All you need to do then is check whether the shutter speeds look vaguely OK, and if so you are away. If they are slow, in my limited experience you probably ought to get it looked at - I suspect that a dragging shutter stretches the springs...
Hope you don't need to worry about any of that and it's all OK!
Adrian